Abstract:
Alertness level is predicted on computers or sliding charts by relationship of sleep drives and wake drives, which are separately moved relative to destination time and time zone differential. Wake drives are moved with home time. Sleep drive is moved with bedtime and sleep debt relative to times and a sleep debt scale, respectively. Resulting displays predict alertness, drowsiness, wake drives in relation to sleep drives, best bedtime, sleep debt and illumination recommendations.

Description:
[0001]     This application is a continuation-in-part of U.S. Ser. No. 10/223,466, filed Aug. 20, 2002. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     All humans go through their lives alternating between the states of sleep and wakefulness. The sleep state is further divided into non-rapid eye movement sleep (NREMS) and rapid eye movement sleep (REMS). The three states, NREMS, REMS, and wakefulness form a Troika of Consciousness Cycle (TCC). Mechanisms in the brain control sleep and alertness in a rhythmic manner, producing the same basic pattern every twenty-four hours, typically eight hours asleep and sixteen hours awake. This daily cycle, or circadian rhythm, is modified by external events: in particular by high-speed air travel traversing several time zones.  
         [0003]     There is a need for better means of predicting the effects of air travel on the circadian rhythm so that travelers can better plan their activities to compensate for the changes which result from such travel.  
       SUMMARY OF THE INVENTION  
       [0004]     The invention can be encapsulated in a computer program or other embodiment, such as a nomogram. The present invention is a Jet Lag Forecaster (JLF), Jet Logger, that helps to plan a traveler&#39;s activities to take advantage of his/her high and low energy periods which occur at strange times following a long jet flight in a generally east-west direction.  
         [0005]     The photo zones east and west are important features of the invention. They indicate the effect that light, either sunlight or artificial, has on the movement of the circadian wake drive in the nychthemeron (a 24 hour period). If a person is exposed to light when a photo zone is over the current time at destination, his circadian wake drive will be accelerated in the direction of the photo zone&#39;s arrow. These zones are very important indicators of when to avoid light as well as when to seek light after arriving at the destination.  
         [0006]     The lengths and heights of these zones are very carefully drawn to indicate the duration and strength of light&#39;s effect on the circadian wake drive. The closer the exposure is to the wake nadir, the stronger the effect of the light. However, within a half hour on either side of the wake nadir it is difficult to tell in which direction light will push the circadian wake drive. After the photo zone west tapers down, light has a nil effect on the placement of the circadian wake drive until photo zone east starts to build up.  
         [0007]     The invention includes a method and apparatus to predict and plan activity levels after rapid changes in time zones, a method to accelerate the movement of the circadian wake drive toward local time and a method to prevent inadvertent movement of the circadian wake drive away from local time, all for providing more rapid recovery from jet lag.  
         [0008]     These and further and other objects and features of the invention are apparent in the disclosure, which includes the above and ongoing written specification, with the claims and the drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  shows a Jet Logger chart made of moveable transparent overlays showing times, time zone shift, sleep and wake drives, sleep debt, bedtime and wake nadirs, with the sleep debt level and time zone indicator both at zero.  
         [0010]      FIG. 2  shows a Jet Logger chart similar to  FIG. 1 , showing increased sleep debt and sleep drive with the time zone shift indicator at zero and the sleep debt level at 3.  
         [0011]      FIG. 3  shows a Jet Logger chart similar to  FIG. 2  with the time zone indicator at zero and the sleep debt level at three hours and with varied psycho-sensory wake drive and deepened wake nadir.  
         [0012]      FIG. 4  shows a Jet Logger chart with showing effects of a three-hour easterly time zone indicator shift and the sleep debt level at two hours.  
         [0013]      FIG. 5  shows a Jet Logger chart similar to  FIG. 4  showing effects of lessening of sleep debt with the time zone indicator shifted three hours to the east and the sleep debt level at one hour.  
         [0014]      FIG. 6  shows a Jet Logger chart similar to  FIG. 5  showing effects of increasing of sleep debt with the time zone indicator shifted three hours to the east and the sleep debt level at four hours.  
         [0015]      FIG. 7  shows a Jet Logger chart similar to  FIG. 5  showing effects of increasing of sleep debt with the time zone indicator at a two-hour easterly shift and the sleep debt level at four hours.  
         [0016]      FIG. 8  shows a Jet Logger chart similar to  FIG. 7  with the time zone indicator shifted two hours to the east and the sleep debt level at three hours.  
         [0017]      FIG. 9  shows a Jet Logger chart with the time zone shift indicator at zero and the sleep debt level at four hours.  
         [0018]      FIG. 10  shows a Jet Logger with the time zone shift indicator at nine hours to the east and the sleep debt level at four hours.  
         [0019]      FIG. 11  shows a Jet Logger chart with the time zone shift indicator at nine hours to the east and the sleep debt level at seven hours showing effects on the drives and nadir of increased sleep debt.  
         [0020]      FIG. 12  shows a Jet Logger chart with the nine-hour time zone shift and the sleep debt level at three hours.  
         [0021]      FIG. 13  shows a Jet Logger chart with the time zone indicator at seven hours east and the sleep debt level at four hours.  
         [0022]      FIG. 14  shows a Jet Logger chart with the time zone indicator at five hours east and the sleep debt level at six hours.  
         [0023]      FIG. 15  shows a Jet Logger chart with the time zone indicator at five hours east and the sleep debt level at four hours.  
         [0024]      FIG. 16  shows a Jet Logger chart with the time zone indicator at three hours east and the sleep debt level at six hours.  
         [0025]      FIG. 17  shows a Jet Logger chart with the time zone indicator at three hours east and the sleep debt level at four hours.  
         [0026]      FIG. 18  shows effects on a Jet Logger chart with the time zone indicator at one-hour east and the sleep debt level at six hours.  
         [0027]      FIG. 19  shows a Jet Logger chart similar to  FIG. 18  with the time zone indicator at one-hour east and the sleep debt level at five hours.  
         [0028]      FIG. 20  shows a Jet Logger chart with the time zone indicator at six hours west and the sleep debt level at two hours.  
         [0029]      FIG. 21  shows a Jet Logger chart with the time zone indicator at six hours west and the sleep debt level at seven hours.  
         [0030]      FIG. 22  shows a Jet Logger chart with the time zone indicator at four hours west and the sleep debt level at six hours.  
         [0031]      FIG. 23  shows a Jet Logger chart with the time zone indicator at three hours west and the sleep debt level at five hours.  
         [0032]      FIG. 24  shows a Jet Logger chart with the time zone indicator at two hours west and the sleep debt level at four hours.  
         [0033]      FIG. 25  shows a return to near normal with the time differential displaced only one hour.  
         [0034]      FIG. 26  shows a chart base with a sleep debt scale, a time at destination indicator and a time zone indicator.  
         [0035]      FIG. 27  shows a transparent overlay for moving left and right with a home time indicator, wake drive indicators and a time zone selector.  
         [0036]      FIG. 28  shows a second transparent overlay for moving up and down and left and right with sleep drive, sleep debt, sleep point, and sleep time indicators.  
         [0037]      FIG. 29  is an alternative embodiment showing a rectangular form and associated instructions. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0000]     How to Use the Jet Logger  
         [0038]     Referring to  FIGS. 1-27 , the Jet Logger  1  will make the next trip a more rewarding experience. One will be able to plan the activities to take advantage of the high and low energy periods that occur at strange times after a jet flight. The purpose of these instructions is simply to show one how to adjust the Jet Logger  1 . They will give only minimal advice on the nature and timing of activities one can do before taking off, during flight, and after landing to minimize or compensate for the accompanying unwanted symptoms. When and how to schedule these activities will depend upon business, competition or pleasure priorities. Armed with this knowledge, the Jet Logger  1  is a powerful tool to ensure a rewarding trip.  
         [0039]     Once one knows what the different lines and shapes represent, and understands a few simple principles, adjusting the Jet Logger  1  is intuitive. Keep the instrument handy while reading these instructions in order to repeat the example adjustments.  
         [0040]     These instructions assume a normal sleep-wake cycle and a usual wake up time and bedtime within an hour and a half of 7:00 am and 11:00 pm.  
         [0000]     Lines and Shapes  
         [0041]     AS shown in  FIGS. 1-24 , a person has two wake drives  3  and  5  that work together trying to make the person alert and one sleep drive  7  that tries to make the person sleep. These drives compete with each other for dominance over a person twenty-four hours a day. Only the one on top determines whether the person is awake or asleep.  
         [0042]     The circadian wake drive  3  is the dark line that undulates across the chart  21 . It rolls along the same up and down path at the same time every day as long as one stays in the same time zone. When a person lands in a new time zone, that person&#39;s circadian wake drive  3  will still be rolling along in time with the clock at home, but it will start shifting to conform to the new local time. This shift usually occurs at the rate of one time zone per day. Until this change is complete, a person will be experiencing jet lag.  
         [0043]     The psycho-sensory wake drive  5  is the dark line covering the circadian wake drive. The psycho-sensory wake drive  5  can expand to reinforce the circadian wake drive when a person wants to stay awake, or it can contract when a person wants to sleep. Its strength can vary from minute to minute as shown in  FIG. 3  depending upon the amount of stimulation it gets from a person and the person&#39;s environment.  
         [0044]     The sleep drive  7  is the dark wave-like area. The sleep drive&#39;s strength is determined only by the amount of sleep a person gets. A sleep drive  7  increases while a person is awake and decreases while a person is asleep. As seen by comparing  FIGS. 1 and 2 , a sleep drive  7  increases as sleep debt  17  increases.  
         [0045]     The time zone indicator  11  is the triangle on the time zone scale  13  at the bottom of the chart  21 . Sliding the time zone indicator  11  right or left indicates the direction and number of time zones a person will cross on a trip. If no anti jet lag measures are taken, after each day at destination move time zone indicator  11  back one time zone towards the center.  
         [0046]     The bedtime indicator  15  is the vertical line passing through the peak  9  of the wave-shaped sleep drive  7 . Using 11:00 pm as bedtime at home, a person obtains a good jet lag forecast if regular bedtime is at a destination within an hour and a half of that time.  
         [0047]     The sleep debt level  17  is a horizontal bar passing through the peak  9  of the sleep drive  7 .  
         [0048]     The sleep debt scale  19  is the rectangular grid in the top half of the chart  21 . The number of hours of insufficient sleep is recorded as sleep debt by moving the sleep debt level  17  upward on this scale.  
         [0049]     The sleep point  23  is where the bedtime indicator  15  crosses the top of the sleep debt level  17 . Sleep point  23  indicates a person&#39;s sleep debt level  17  on sleep debt scale  19  at bedtime  15 . The later a person goes to bed, the larger the person&#39;s sleep debt. Likewise the earlier a person goes to bed, the smaller it is. Therefore, to keep the sleep point  23  in its proper place, a person must move the sleep debt level  17  up or down as many rows as the number of hours the bedtime indicator  15  is moved right or left respectively.  
         [0050]     The wake nadir  25  is the small triangle at the lowest point on the circadian wake drive  3 . It indicates the most difficult time to stay alert. At home, the wake nadir  25  usually occurs between 4:00 and 5:00 am, but after jet travel it can occur at any hour.  
         [0051]     The photo zones east  27  and west  29  are the two light curves covering arrows  31  and  33  just before and just after the wake nadir  25 . Exposure to light during the time zones covered by either of these photo zone curves  27 ,  29  will shift the circadian wake drive  3  in the direction indicated by the related arrow  31 ,  33 . The closer the light exposure is to the wake nadir  25  the greater is the shift, however, it is difficult to predict the direction of the shift when the exposure is very near the wake nadir.  
         [0000]     Accumulation of Sleep Debt  
         [0052]     It is normal to have up to four hours sleep debt  17 . A person accumulates one hour sleep debt for every hour the person sleeps less than the usual amount, and a person accumulates a half hour sleep debt for every one hour of poor quality sleep. However, if a person sleeps more than the person&#39;s usual amount, the person subtracts one hour from the person&#39;s sleep debt for every extra hour the person sleeps. When calculating sleep debt level  17 , hours are rounded off to the nearest whole number.  
         [0000]     At Home with No Sleep Debt  
         [0053]     In  FIG. 1 , the sleep debt level  17  and time zone indicator  11  are both at zero. This tells that the person depicted is highly alert, for example between the hours of 7:00 am and 11:00 pm in his home time zone. The relative heights of the wake drive  3 ,  5  and sleep drives  7  are important. The higher on the chart  21  a wake drive  3 ,  5  or sleep drive  7 , the stronger it is. When a person&#39;s wake drives  3 ,  5  are high above the sleep drive  7  the person is very alert. When a person&#39;s wake drives  3 ,  5  are close to the sleep drive  7 , the person is drowsy. When a person&#39;s sleep drive  7  is above both the wake drives  3 ,  5 , the person is asleep.  FIG. 1  shows the ideal position of the circadian wake drive  3  relative to the sleep drive  7 . Notice that both rise and fall at the same times.  
         [0054]     In  FIG. 1  the sleep drive  7  is below the circadian wake drive  3  during all parts of the day. No expansion of the psycho-sensory wake drive  5  is necessary to stay awake.  
         [0000]     Volatility of the Psycho-Sensory Wake Drive  
         [0055]     The main cause of jet lag is a displaced circadian wake drive  5 . The circadian wake drive  5  tends to remain aligned with the at home when a person is at another location or destination in a different time zone. Jet lag is usually aggravated by an excessive sleep debt. A person&#39;s psycho-sensory wake drive  5  neutralizes the symptoms of jet lag by expanding, as shown in  FIG. 3 . Its results, however, are not without limit or effort. To help a person understand how the psycho-sensory wake drive  5  can combat these symptoms, let us first look at how it functions at home in a normal individual with a three hour sleep debt.  
         [0056]     Move the sleep debt level  17  upward three hours as shown in  FIG. 2 . Notice that the sleep drive  7  is now above the wake drives  3 ,  5  between 7:00 and 8:00 in the morning, 12:30 and 5:00 in the afternoon, and 9:30 and 11:00 at night. This is normal, but if no adjustments are made to the subject&#39;s wake and/or sleep drives the subject would be asleep at these times. The subject cannot immediately change the strength of his circadian wake drive  3  or his sleep drive  7 . It takes days to change them, but the strength of his psycho-sensory wake drive  5  can be changed in seconds, as shown in  FIG. 3 . Anything that stimulates him physically or mentally increases its strength. These stimulants include alarm clocks, lights, coffee, physical activity, conversation—the list is endless. There is also a long list of factors that decrease its strength, like silence, darkness, alcohol, sleeping pills, physical inactivity, anything monotonous.  
         [0000]     Typical Psycho-Sensory Wake Drive Reactions to Daily Events.  
         [0057]     Let&#39;s follow the subject from wake up in the morning to bedtime at night on his birthday ( FIG. 3 ). The subject is awakened at 7:00 am by an alarm clock that shoots his psycho-sensory wake drive  5  above his sleep drive. He gets ready for the day, eats breakfast, and drives to work. Boring paper work causes his psycho-sensory wake drive  5  to dip around 10:00 am, but he won&#39;t doze off at this time because his circadian wake drive  3  is higher than his sleep drive. An exciting lunch date at noon perks up his psycho-sensory wake drive  4 , but the aftereffects of the luncheon cocktail plus duller paper work reduce it during mid afternoon. He is very drowsy between 3:00 and 4:00 pm. At 5:00 pm his office surprises him with a birthday party. He has dinner and a glass of wine at 7:00 pm and watches TV the remainder of the evening. His psycho-sensory wake drive  5  gradually declines until 9:00 pm when he momentarily dozes off. Immediately after that an exciting movie appears on TV and he perks up until it ends at 11:00 pm.  
         [0058]     As can be seen, the psycho-sensory wake drive  5  is affected by various stimulants and depressants throughout the day. A person can control some of these stimulants but not others. The Jet Logger  1  does not show the expansion and contraction of the psycho-sensory wake drive  5 . A person will know how much wake drive  5  is needed in every hour of the day at the destination just by looking at the relationship of the circadian wake drive  3  to the sleep drive. As the person will see in the examples below, with reference to  FIGS. 4-24 , the need for psycho-sensory wake drive  5  will occur in very different times at the destination than it does at home.  
         [0059]     The sleep-wake scenarios that a person can encounter when jet traveling are endless, depending upon the direction of travel, the number of time zones  12  crossed, the size of the person&#39;s sleep debt  17 , the person&#39;s bedtime  16  and the person&#39;s wake up time  18  at destination  20 . The few examples given below are sufficient to show how to adjust the Jet Logger  1 .  
         [0000]     Jet Logger Adjustments for All Trips  
         [0060]     Before Departure  
         [0061]     1. Move the sleep debt level  17  to indicate sleep debt at start of trip.  
         [0062]     2. Move the time zone indicator  11  east or west as many time zones  12  as will be crossed, and return the bedtime indicator  15  to 11:00 pm at home time  22 .  
         [0063]     On Arrival  
         [0064]     3. Move the sleep debt level  17  up or down to adjust for amount of sleep during flight. If day flight, reduce sleep debt level  17  one row for each hour slept. If night flight reduce or increase sleep debt level  17  one row for each hour slept more or less than usual night at home respectively.  
         [0065]     First Night After Arrival  
         [0066]     4. Move the sleep point  23  and bedtime indicator  15  to bedtime at the destination time  24 . Move the sleep point  23  and the sleep debt indicator up or down on the sleep debt scale  19  as many rows as the number of hours the bedtime indicator  15  is moved right or left respectively.  
         [0067]     First Morning at Destination  
         [0068]     5. Move the sleep debt level  17  up or down depending on quantity and quality of the last night&#39;s sleep. Move the debt level indicator  17  upward one hour above the level in step 4 for every hour slept less than in a usual night at home, and one hour upward for every two hours of poor quality sleep. Move the debt level indicator  17  downward one hour for every hour slept more than in a usual night at home.  
         [0069]     6. Move the time zone indicator  11  one to two time zones towards zero. Usually, the circadian wake drive  3  returns to normal at the rate of about one time zone per day. Light exposure during the photo zones can retard or accelerate that rate depending on the direction of the appropriate arrow  31 ,  33  in the photo zone.  
         [0070]     Each Next Night and Morning  
         [0071]     Repeat steps 4-6 until back to normal sleep-wake schedule and the time zone indicator  1  is at zero.  
         [0072]     When returning home one repeats the steps 1-6.  
         [0000]     Examples of Jet Logger Adjustments.  
         [0073]     Eastbound, Three Time Zones, Daytime Flight.  
         [0074]     Before Departure, as Shown in  FIG. 4 :  
         [0075]     1. Move the sleep debt level  17  to row  2  to indicate two hours of sleep debt  17  (assuming the person is alert normal).  
         [0076]     2. Move the time zone indicator  11  three zones rightward and return the bedtime indicator  15  to 11:00 pm at home.  
         [0077]     On Arrival  
         [0078]     3. No adjustment is made to sleep debt level  17  (assuming person did not sleep on the flight). The Jet Logger  1  now should look like  FIG. 4 . Notice that 11:00 pm at home time  22  is 2:00 am at destination time  20 . Also notice that at midnight at destination time  20 , the person&#39;s sleep drive  7  is just below the person&#39;s circadian wake drive  5 . A person would have difficulty falling asleep at that time.  
         [0079]     First Night After Arrival  
         [0080]     Let us say the person decides to go to bed at 1:00 am. Look at  FIG. 4  to see where the person&#39;s sleep drive  7  is at 1:00 am. That is where the sleep point  23  must now be moved to, 10:00 pm at home time  22 .  
         [0081]     4. Move the sleep point  23  one hour leftward to 1:00 am destination time  20  and 1 row downward to indicate one less hour sleep debt  17  (the hour between 2:00 am and 1:00 am destination time  20 ). The Jet Logger  1  now should look like  FIG. 5 .  
         [0082]     First Morning at Destination  
         [0083]     The person sleeps until 7:00 am destination time  20  the next morning and the person&#39;s sleep debt  17  is larger for two reasons: 1) the person slept two hours less (1:00 to 7:00) than the usual eight hour amount, and 2) the person&#39;s Jet Logger  1  indicates ( FIG. 5 ) that the quality of sleep between 1:30 and 2:30 am was poor.  
         [0084]     5. Move sleep debt level  17  upward three additional hours to row  4  (2 for quantity and 1 (one hour halved then rounded upward) for quality of sleep). The Jet Logger  1  should look like  FIG. 6 . Notice that the person needed an alarm to wake up at 7:00 am. Also notice that the person&#39;s wake nadir  25  is now at 7:30 am. Light exposure before that time moves (arrow  31 ) the person&#39;s circadian wake drive  3  further eastward. Light exposure after that time would return it to the west. Jet lag is reduced when the triangular time zone indicator  11  at the bottom on the chart  21  moves towards zero. Therefore a person exposes himself to light when in the photo zone whose arrow point in the direction that will push or pull the time zone indicator  11  towards zero. The person avoids light when the arrow will move it away from zero. In that case one tries to avoid light before 7:30 am, and tries to get as much light as possible between 8:00 am and noon.  
         [0085]     6. Move the time zone indicator  11  one time zone leftward to time zone  2 . This person was unable to get out in the bright sunlight, but was exposed to the equivalent of office lighting. The Jet Logger  1  should now look like  FIG. 7 . Notice that after rising to an alarm at 7:00 am a person will need to expand the psycho-sensory wake drive  5  to keep alert until late morning and during the midday circadian wake drive dip, which will now occur around 5:00 pm. A person will not need much psycho-sensory wake drive  5  to be alert around 9:00 pm.  
         [0086]     Second Night.  
         [0087]     Repeat step 4. Although  FIG. 7  indicates that a person could fall asleep at 11:00 pm, the evening circadian wake drive plateau  5  would soon wake the person up. The person would do better to go to bed at midnight (10:00 pm at home, time  22 ).  
         [0088]     4a. Move the sleep point  23  one hour leftward to midnight and one row downward to indicate three hours sleep debt. The Jet Logger  1  should look like  FIG. 8 .  
         [0089]     Second Morning.  
         [0090]     Repeat steps 5-6. Except for a brief period between 1:30 and 2:00 am last night, the quality of the person&#39;s sleep was good, but the person slept one hour less (12:00 to 7:00) than the usual eight hour amount.  
         [0091]     5a. Move the sleep debt level  17  upward one hour to row  4 . The person&#39;s wake nadir  25  is now at 6:30 am. Since the person slept until 7:00 am, the person avoided light before the wake nadir. It was a bright sunny day. The person had breakfast in front of a large window and spent the entire morning outdoors.  
         [0092]     6a. Move the time zone indicator  11  two time zones leftward to time zone O. The Jet Logger  1  should now look like  FIG. 9 . The person should have no remaining jet lag. The sleep debt level  17  is high normal, and the person should have no difficulty going to sleep at 11:00 pm or an hour earlier to reduce the sleep debt.  
         [0093]     Eastbound, Nine Time Zones, Night Plus Daytime Flight  
         [0094]     A person will depart late afternoon and arrive at the destination the next day at 4:00 pm.  
         [0095]     Before Departure  
         [0096]     1. Move the sleep debt level  17  to row  4  (assuming the person has a high normal sleep debt).  
         [0097]     2. Move the time zone indicator  11  nine time zones to the right, and return the bedtime indicator  15  to 11:00 pm at home time  22 . The Jet Logger  1  should look like  FIG. 10 . Notice that the person&#39;s wake nadir  25  is at 1:30 pm destination time  20 . During the flight if one is sitting next to a window, one should keep the shade down until that time, then raise it and look at the white clouds. Never look directly at the sun. One should try to keep exposed to bright light until late afternoon. From 7:00 pm until 4:00 am, destination time, light exposure will have negligible effect on the circadian wake drive  3 .  
         [0098]     On Arrival  
         [0099]     During the flight the person slept three hours less than the usual amount at home.  
         [0100]     3. Move the sleep debt level  17  upward three hours to row  7 . The Jet Logger  1  now should look like  FIG. 11 . Notice that 9:00 pm at destination is noon at home. Since the person has seven hours sleep debt, the person will not have any difficulty falling asleep any time after arrival. But, the circadian wake drive  3  is rising during that time so the person would not sleep very long. The chances of continuous sleep are slight before 4:00 am, which is 7:00 pm at home. That&#39;s when the circadian wake drive  3  starts to level off before declining. It is important not to nap during this day, since napping would reduce the sleep drive, which is necessary to enable the person to sleep that night.  
         [0101]     First Night After Arrival  
         [0102]     Let us say a person decides to go to bed at 4:00 am. Observe in  FIG. 11  where the sleep drive  7  will be at that time. That is where the sleep point  23  must now be moved.  
         [0103]     4. Move the sleep point  23  four hours leftward to 4:00 am and four rows downward to indicate three hours sleep debt  17 .  
         [0104]     The Jet Logger  1  as shown in  FIG. 12  tells several important things. One is that the person will have a difficult time sleeping between 4:30 and 8:00 am. The person may fall asleep quickly at 4:30 am, but will awaken in about a half hour when the sleep drive  7  dips below the circadian wake drive  3 . Since the photo zone east  27  begins around 4:00 am and continues to rise until the wake nadir  25 , which occurs about 1:30 pm, it is important that the person avoid light and stay inactive during that time. The sleep drive  7  will show a saw tooth pattern above and the circadian wake drive  3  until about 8:00 am. The person will then be able to sleep soundly until after the wake nadir  25 . Before going to sleep it is important to make the room as light proof as possible. If one has to awaken before 1:30 pm, wear dark glasses until that time.  
         [0105]     First Morning at Destination  
         [0106]     Let us say a person was able to sleep until 8:00 am. The person spent nine hours in bed, but must deduct half of the four hours of poor quality sleep. That leaves the person with a net of seven hours of sleep, one hour less than usual.  
         [0107]     5. Move sleep debt level  17  upward one row to level  4 . That move is based on the assumption the person was able to spend most of the afternoon in the sunlight after being in darkness during the photo zone east  27 . That should cause the circadian wake drive  3  to advance two hours rather than the usual one hour per day.  
         [0108]     6. Move the time zone indicator  11  two time zones leftward to time zone  7 . The Jet Logger  1  should now look like  FIG. 13 .  
         [0109]     Second Night  
         [0110]     Repeat step 4. Let us say the person is able to resist napping during the day and go to sleep again at 4:00 am.  
         [0111]     4a. No adjustment to bedtime.  
         [0112]     Second Morning  
         [0113]     Repeat steps 5-6. The person sleeps until 11:00 am. That gives the person seven hours in bed, which is one hour less than the usual. Also the quality of sleep was poor between 4:30 am and 6:30 am.  
         [0114]     5a. Move sleep debt level  17  upward a total of two hours to level  6  (one hour for quantity and one hour for quality of sleep). Notice that the person&#39;s wake nadir  25  occurred at 11:30 am that morning. That assumes that the person got several hours of sunlight between noon and 4:30 pm in addition to the darkness before the wake nadir  25 . That causes the circadian wake drive  3  to again advance two hours rather than the usual one hour.  
         [0115]     6a. Move the time zone indicator  11  two time zones leftward to time zone  5 . The Jet Logger  1  should now look like  FIG. 14 .  
         [0116]     Third Night  
         [0117]     Repeat step 4. Tonight the person should be able to go to sleep at 2:00 pm.  
         [0118]     4b. Move the bedtime indicator  15  two hours leftward to 2:00 am and the sleep debt indicator  17  two rows downward to indicate four hours sleep debt. The Jet Logger  1  should look like  FIG. 15 .  
         [0119]     Third Morning  
         [0120]     Repeat steps 5-6. The person sleeps until 9:00 pm. That again gives the person seven hours in bed, including poor quality of sleep between 2:30 and 4:30 am, resulting in two hours increase in sleep debt.  
         [0121]     5b. Move the sleep debt level  17  upward two hours to level  6 . This assumes the person got the optimum darkness and bright light around the wake nadir  25 , which occurred that morning at 9:30.  
         [0122]     6b. Move the time zone indicator  11  two time zones leftward to time zone  3 . The Jet Logger  1  should now look like  FIG. 16 .  
         [0123]     Fourth Night  
         [0124]     Repeat step 4. Tonight the person should be able to go to sleep at midnight.  
         [0125]     4c. Move the bedtime indicator  15  and sleep point  23  two hours leftward to midnight and two rows downward to indicate four hours sleep debt. The Jet Logger  1  should now look like  FIG. 17 , which is similar to both  FIGS. 13 and 15 . The only difference is the circadian wake drive  3  is four hours ahead of that in  FIG. 13  and two hours ahead of that in  FIG. 15 . That enables the person to go to sleep two hours earlier than the previous night.  
         [0126]     Fourth Morning  
         [0127]     Repeat steps 5-6. The person sleeps until 7:00 pm. That again gives the person seven hours in bed, including poor quality of sleep between 12:30 and 2:30 am, resulting in two hours increase in sleep debt.  
         [0128]     5c. Move the sleep debt level  17  upward two hours to level  6 . That assumes the person gets the optimum darkness and bright light around the wake nadir  25 , which occurred that morning at 7:30 am.  
         [0129]     6c. Move the time zone indicator  11  two times zone leftward to time zone  1 . The Jet Logger  1  should now look like ( FIG. 18 )  
         [0130]     Fifth Night  
         [0131]     Repeat step 4. Tonight the person should be able to go to sleep at 11:00 pm.  
         [0132]     4d. Move the bedtime indicator  15  and sleep point  23  one hour leftward to 11:00 pm and one row downward to indicate five hours sleep debt. The Jet Logger  1  should now look like  FIG. 19 .  
         [0133]     Fifth Morning  
         [0134]     Repeat steps 5-6. The person got the normal quantity and quality of sleep last night.  
         [0135]     5d. No adjustment to sleep debt.  
         [0136]     6d. Move the time zone indicator  11  one time zone leftward to time zone O.  
         [0137]     Sixth Night  
         [0138]     The person&#39;s circadian rhythm is back to normal, so the person is now able to go to bed earlier than the usual time at home if the person would like to reduce the sleep debt.  
         [0139]     Westbound, Six Time Zones, Daytime Flight.  
         [0140]     Let us assume a person will arrive at the destination early evening.  
         [0141]     Before Departure  
         [0142]     We assume the person has a high normal sleep debt.  
         [0143]     1. Move the sleep debt level  17  to the four hour level.  
         [0144]     2. Move the time zone indicator  11  six time zones to the left, and return the bedtime indicator  15  to 11:00 pm at home.  
         [0145]     On Arrival  
         [0146]     During the flight the person slept two hours.  
         [0147]     3. Move the sleep debt level  17  downward two hours to row  2 . The Jet Logger  1  should look like  FIG. 20 . Notice that 11:00 pm at home time  22  is 5:00 pm at destination time  20 . Although the person can fall asleep any time after 5:00 pm, it is not advisable to do so since the person would then have difficulty sleeping beyond 2:00 am. The person should try to stay up until 10:00 pm (4:00 am at home) gaining as much exposure to bright light as possible up to but not beyond that time (10:00 pm) since the wake nadir  25  is at 10:30 pm.  
         [0148]     First Night After Arrival  
         [0149]     Let us say the person goes to bed at 10:00 pm. Look at  FIG. 20  to see where the person&#39;s sleep drive  7  will be at that time. That is where the sleep point  23  must now be moved. Remember every one hour the bedtime indicator  15  is moved rightward the sleep debt level  17  must be moved one row upward.  
         [0150]     4. Move the sleep point  23  five hours rightward to 10:00 pm and five rows upward to indicate seven hours sleep debt. The Jet Logger  1  should look like  FIG. 21 .  
         [0151]     First Morning at Destination  
         [0152]     Assume the person sleeps until 7:00 am. The person received one hour more than the usual amount of sleep.  
         [0153]     5. Move sleep debt level  17  downward one hour to row  6 . That assumes the person got ample bright light before going to bed at 10:00 pm and slept in darkness after the wake nadir  25  at 10:30 pm.  
         [0154]     6. Move the time zone indicator  11  two hours rightward to time zone  4 . The Jet Logger  1  should look like  FIG. 22 .  
         [0155]     Second Night  
         [0156]     Repeat step 4. The person goes to sleep at 10:00 pm.  
         [0157]     4a. No adjustment to sleep point.  
         [0158]     Second Morning  
         [0159]     Repeat steps 5-6. The person again sleeps nine hours until 7:00 pm.  
         [0160]     5a. Move sleep debt level downward one hour to level  5 . The person&#39;s wake nadir  25  occurred at 12:30 am, and the person was unable to be exposed to bright light several hours prior to it.  
         [0161]     6a. Move the time zone indicator  11  one hour rightward to time zone  3 . The Jet Logger  1  should look like  FIG. 23 .  
         [0162]     Third Night  
         [0163]     Repeat step 4. The person again goes to sleep at 10:00 pm.  
         [0164]     4b. No adjustment to sleep point.  
         [0165]     Third Morning  
         [0166]     Repeat steps 5-6. The person again sleeps nine hours until 7:00 pm.  
         [0167]     5b. Move sleep level downward one hour to level  4 .  
         [0168]     6b. Move the time zone indicator  11  one time zone rightward to time zone  2 . The Jet Logger  1  should look like  FIG. 24 .  
         [0169]     Fourth Night  
         [0170]     Repeat step 4.  FIG. 24  indicates that the person&#39;s energy levels during the day are approximately normal except for the late evening. The person should now be able to go to sleep at 9:00 pm and sleep until 7:00 am.  
         [0171]     4c. Move sleep point  23  one hour leftward to 9:00 pm and one row downward to indicate three hours of sleep debt.  
         [0172]     Fourth Morning  
         [0173]     Repeat steps 5-6. The person slept two hours more than the usual.  
         [0174]     5c. Move sleep debt level  17  downward two hours to level  1 .  
         [0175]     6c. Move the time zone indicator  11  one time zone rightward to time zone  1 . The Jet Logger  1  should look like  FIG. 25 .  
         [0176]     Fifth Night  
         [0177]      FIG. 25  indicates that the person&#39;s energy levels are now high all day and late evening. The person should be able to go back to the regular 11:00 pm to 7:00 am sleep schedule.  
         [0178]     Referring to  FIG. 26 a  chart base  51  has a sleep debt scale  19 , a time at destination indicator  20  and a time zone indicator  11 .  
         [0179]     Referring to  FIG. 27 a  transparent overlay  53  overlies the chart base  51  and moves left and right. Overlay  53  has a home time indicator  22 , lines to represent wake drives  3  and  5  and a time zone selector  11 .  
         [0180]     Referring to  FIG. 28 a  second transparent overlay  55  overlies chart base  51  and overlies or underlies transparent overlay  53  and moves up and down and left and right. Transparent overlay  55  has a transparent hatched wave shape to show sleep drive  7 , and has sleep debt indicator  17 , sleep point indicator  23 , and bedtime indicator  15 .  
         [0181]     Assembling the base chart  51  and overlays  53  and  55  forms the charts  1  of  FIGS. 1-25 .  
         [0182]     A frame, not shown holds the overlays on the chart to form an adjustable Jet Lag Forecaster  1 .  
         [0183]     The base chart and overlay are preferably reproduced in software in a computer so that a hard drive or replaceable drive may be used with a laptop or hand-held computer to chart, predict, and record sleep and wake drive relationships and times of effectiveness.  
         [0184]      FIG. 29  shows another alternative embodiment of a jet lag forecaster chart  101 . The chart  101  includes a base sleeve  103  that may or may not be connected to accompanying instructions sheets  119  or booklets. The instruction sheets  119  or booklets describe the purpose and functionality of the jet lag forecaster chart  101 . A slide  107  is inserted into the base sleeve  103 .  
         [0185]     The base sleeve  103  may have one or more openings  105  that reveal information on the slide  107  located within the base sleeve  103 . The base sleeve  103  generally has one or more indications of a local clock  109 . The local clock  109  represents the time at a destination after a flight or at home before a flight. Other indicators include a time zone indicator  121 .  
         [0186]     The slide  107  contains information viewable through the openings  105  of the base sleeve  103 . A jet lag forecaster chart  101  may come with one or more slides  107 . Each slide  107  is individualized for a specific wake time  117 . For example, one slide  107  may show information for a normal wake up time of 7 a.m., while a different slide  107  may show information for a normal wake up time of 9 a.m. Each individual&#39;s sleep and wake drives take on a similar shape. Therefore, the jet lag forecaster is useful for each individual user. The generic human responses to light and melatonin, as well as general alertness, are shown in the Figures. Selecting a normal wake up time  117  performs individualization. The openings  105  reveal information on the slide  107 , such as responses to light  111 , biological alertness  113  and responses to melatonin  115 . The base sleeve  103  also includes a time zone counter  121 . A triangle or other shape  123  indicates a central base time.  
         [0187]     In a preferred embodiment, the base sleeve  103  would have three openings revealing information on responses to light  111 , biological alertness  113  and responses to melatonin  115  in separate openings.  
         [0188]     The slide  107  contains information complementary to the information on the base sleeve  103 . Information on responses to light  111  shows the best times of day to seek and avoid light. Indicators may include arrows and graphs  125  to indicate the strength and direction of the effect of light. Information on biological alertness  113  includes a wavy line  127  representing overall alertness levels. The slide  107  may also include colored indicators of alertness levels. For example, lighter colors indicate higher alertness levels and darker colors represent lower alertness levels. Alternatively, high alertness may be shown in green, medium alertness in yellow and low levels of alertness in red. Other combinations of indicators are possible. The information on biological alertness  113  may also include indicators of home bedtime and wake up time  129 . Information on responses to melatonin  115  shows the best times of day to take or avoid taking melatonin. Indicators may include arrows and graphs  131  to indicate the strength and direction of the effect of melatonin. The slide  107  also contains a triangular or other shape  133  complementary to the shape  123  on the base sleeve  103 . When the shapes  123 ,  133  are aligned, no jet lag is present. The slide  107  may also contain directional indicators  135  to show a user which direction to move the slide  107  when moving east or west.  
         [0189]     The embodiment of  FIG. 29  is used in a similar manner to those embodiments described above. A user moves the slide  107  relative to the base sleeve  103  based on the number of time zones crossed. The user then looks to determine the best times of day to schedule activity, seek or avoid light, or take or avoid melatonin. The jet lag forecaster chart  101  allows a user to successfully optimize travel plans and minimize the effects of jet lag. The user then adjusts the relative positions of the base sleeve  103  and the slide  107  based upon the amount of sleep, exposure to light and taking of melatonin. The process is repeated until no more jet lag exists.  
         [0190]     The jet lag forecaster is not limited to the above-described embodiments. The jet lag forecaster of the present invention may have different shapes and forms. For example, the jet lag forecaster may be square, rectangular, circular or other shapes. The slide is moved relative to a base to identify the alertness levels of a user.  
         [0191]     While the invention has been described with reference to specific embodiments, modifications and variations of the invention may be constructed without departing from the scope of the invention, which is defined in the following claims.