Devices and methods for maintaining an alert state of consciousness through brain wave monitoring

Disclosed are devices for monitoring and maintaining an alert state of consciousness in a subject wearing the device An alert mental state is maintained through monitoring of brain wave patterns to detect if a transition from an alert to a non-alert mental state is about to occur, or has occurred. If so, a stimulus, e.g., an audible tone, is provided until such time as an alert mental state, as assessed by brain wave activity, is restored. Also disclosed are methods for maintaining an alert mental state, as well applications for such devices and methods.

TECHNICAL FIELD OF THE INVENTION 
The invention relates to devices and methods for maintaining an alert state 
of consciousness. In particular, this invention relates to devices and 
methods for monitoring brain waves to detect patterns associated with a 
non-alert state of consciousness, in which event a stimulus is then 
provided to restore an alert mental state. 
BACKGROUND OF THE INVENTION 
Maintenance of an alert mental state of consciousness is important in many 
fields for many reasons. For example, the American Medical Association's 
Council on Scientific Affairs published a report indicating that driver 
drowsiness and fatigue are involved in at least about 1.5% of the nation's 
annual 6.3 million vehicle accidents. Of those accidents involving 
drowsiness, about 96% involved passenger vehicles; the remainder involved 
trucks. In addition to the transportation industry, many other fields 
incur substantial revenue and productivity losses due to individuals 
unintentionally transitioning from an alert state of consciousness to a 
non-alert state. Avoiding or delaying such transitions would have enormous 
economic and societal benefit. 
Prior to this invention, no device existed which could prevent or delay the 
onset of an unintentional transition from an alert mental state to a 
non-alert state of consciousness through the monitoring of brain wave 
patterns. Instead, in order to prevent such transitions, various other 
approaches have been applied. For example, chemical stimulants have long 
been used in order to maintain an alert state of consciousness for a 
period longer than would be experienced absent the stimulant. 
Alternatively, in some fields time periods during which a particular 
function requiring that an alert state of consciousness be maintained have 
been established in order to ensure the desired level of consciousness is 
maintained throughout. 
More recently, several devices have been developed which monitor and 
respond to physical manifestations of fatigue or drowsiness. For example, 
U.S. Pat. No. 5,402,109 describes an eyeglass-attachable alarm signal 
device designed to prevent automobile and truck drivers from falling 
asleep while driving. The device employs a small slide-adjustable light 
emitter which produces a beam of a narrow-band light to optically sense 
whether the driver's eyelids are opened or closed. The light beam is aimed 
across the surface of the driver's eye, just above the eyeball, between 
the eyelids, and it is sensed in the opposite corner of the eye by a light 
sensor. When the device detects that a driver's eyes have been closed for 
longer than a predetermined time, e.g., about one second, an electronic 
circuit activates an alarm. 
Another device to monitor and restore alertness is described in U.S. Pat. 
No. 5,626,145. Specifically, that device automatically detects alertness 
in a subject by collecting brain wave data from a subject using an 
electroencephalogram or magnetoencephalogram. The brain wave data is then 
separated from other data, e.g., data resulting from eye blinks, chewing, 
and other movements not related to brain activity, using a zero phase 
quadratic filter. The non-brain wave data is then further analyzed to 
detect alertness. Thus, these devices do not monitor states of 
consciousness by analysis of brain waves or brain wave patterns, but 
instead rely on physical manifestations of states of consciousness. 
In contrast, it is the object of this invention to provide devices which 
allow an alert state of consciousness to be maintained through the use of 
a device which monitors and interprets brain wave patterns of an 
individual wearing the device. When the device detects in the wearer a 
brain wave pattern associated with a non-alert state of consciousness, a 
transient physical stimulus is then provided to restore the desired mental 
state. 
SUMMARY OF THE INVENTION 
One aspect of the invention concerns devices for maintaining a state of 
mental alertness. Generally, such devices include, but are not limited to, 
one or more brain wave sensors used to monitor one or more brain wave 
types in a subject in whom an alert mental state is to be maintained, a 
processor capable of analyzing brain wave patterns detected by the brain 
wave sensor(s) to determine if the subject is in an alert mental state, an 
alarm component for delivering a stimulus to capable of restoring an alert 
mental state, and a power supply. 
In preferred embodiments of this aspect of the invention, the brain wave 
sensors used in the device comprise electrodes that make contact with skin 
of the subject's, or user's, head. In such embodiments, the electrode(s) 
is(are) configured to detect the desired brain wave(s) to be analyzed. If 
necessary, the sensor (or processor) also includes elements, e.g., 
circuitry, required for the sensor (e.g., an electrode) to produce a 
signal (e.g., a digital signal) that can be input into an analyzed by the 
processor. In those embodiments where the sensor is not operably connected 
to the processor, for example, the sensor(s) detects brain waves, and this 
information is transmitted to a remotely positioned processor integrated 
with an appropriate receiver, etc. 
In these and other embodiments of this aspect of the invention, the brain 
wave sensor(s) used in the device can detect at least one brain wave type, 
or form (e.g., alpha, beta, delta, or theta brain waves), and preferably 
can detect a plurality of, and preferably all brain wave forms, including 
such forms as alpha spindles and theta bursts. 
In preferred embodiments of the device according to the invention, the 
processor is operably associated with (e.g., functionally connected to) 
the brain wave sensor(s) employed, and is capable of being worn by the 
user wearing the brain wave sensor(s). Preferably, the brain wave 
pattern(s) and/or wave(s) detected by the brain wave sensor(s) are input 
into the processor and analyzed. Typically, brain wave data (i.e., data 
concerning one or more brain wave forms or and/or patterns) is analyzed by 
comparing the detected brain wave(s) and/or brain wave pattern(s) against 
a library of brain wave(s) and/or pattern(s) (typically stored in a memory 
operably connected to the processor) in order to determine if a brain wave 
form and/or pattern input into the processor is indicative of a non-alert 
mental state. In particularly preferred embodiments, the library of brain 
wave(s) and/or pattern(s) is derived previously from the same subject 
while in an alert state of consciousness. Alternatively, the library may 
be based on data gathered from a plurality of test subjects during the 
course of vigilance testing, or other testing designed to produce 
detectable performance decrements, particularly a non-alert mental state, 
during the course of the test. 
In preferred embodiments of this aspect of the invention, the processor 
analyses digital signals derived from the brain wave data detected by the 
brain wave sensor(s). Preferably, the subject's brain wave activity is 
analyzed at least once every fifteen seconds, with monitoring and analysis 
of the subject's brain waves and/or patterns at least once per second 
being particularly preferred. Especially preferred periods for frequencies 
of analysis are once per 0.1, 0.05, 0.01, or 0.001 second. Of course, 
continuous monitoring may also be performed, particularly when the period 
of time the user uses the device is of short duration, or when power 
requirements are not a concern, for example, when power for the device is 
supplied from a source such as a vehicle's electrical system. 
In particularly preferred embodiments, the processor can also calculate one 
or more brain wave ratios, wherein the amount of a particular brain wave 
type over a given time unit is compared to the amount of another brain 
wave type over an equal, particularly the same, time period. Such 
calculations are well known in the art, e.g., integration. In such 
embodiments, it is useful to detect not only the period over which one or 
more brain wave types occurs, but also the amplitude(s) of such activity 
during that period. When a ratio, or that correlates with a non-alert 
state is detected, or preferably, when several such ratios are determined 
within a given period, the processor may then perform a routine to 
generate a stimulus to restore an alert mental state. Particularly 
preferred ratios include an alpha:beta ratio. What constitutes a ratio 
that correlates with a non-alert mental state can vary, particularly from 
person to person, as those in the art will appreciate. For this reason, 
the ratio(s) used for a particular user are preferably determined in 
advance, for example, by vigilance testing, where observable decrements in 
performance of one or more tasks are correlated with brain wave activity. 
When the performance level of the task(s) being performed declines below a 
particular level, for example, below about 75%, preferably below about 
80%, more preferably below about 85%, even more preferably below about 
90%, especially more than below about 95% of maximum performance, the 
brain wave(s) and/or patterns then detected are determined to correlate 
with a non-alert mental state. As those in the art will appreciate, what 
constitutes a non-alert mental state may vary depending upon the task 
(e.g., driving, listening, operating dangerous machine tools, etc.) for 
which a minimum desired level of consciousness is required. 
In yet other preferred embodiments of this aspect of the invention, upon 
detection of a non-alert state, the device's alarm component is actuated 
to emit a stimulus, or series of stimuli, perceptible to the user in a 
manner sufficient to transition the subject from a non-alert mental state 
to an alert mental state. In certain of these embodiments, the stimulus 
emitted from or produced by the alarm component is selected from the group 
consisting of an auditory stimulus, a visual stimulus, an electrical 
stimulus, a vibratory stimulus, and a combination of more than one of the 
foregoing stimuli. In particularly preferred embodiments employing an 
auditory stimulus, the alarm component of the device is positioned in or 
adjacent to an ear canal of the user in a manner such that when the 
stimulus is emitted, it can be perceived by the user and restores an alert 
mental state in the user. Particularly preferred are devices wherein the 
auditory stimulus, or one or more other stimuli, can be selected by the 
user wearing the device. 
In other preferred embodiments, the device's power supply comprises one or 
more batteries. 
Preferably a device according to the invention comprises one or more brain 
wave sensors integrated into a headband that can be worn by the user. 
Preferably, the device also includes an alarm and processor such that when 
the components are integrated they comprise a single removable apparatus 
that can be worn comfortably on a user's head. Even more preferred are 
such devices that further comprise a power supply. Other components, e.g., 
a transmitter, receiver, other physiological monitoring devices, etc., can 
also be incorporated into a device according to the invention. 
Another aspect of this invention concerns methods for monitoring an alert 
state of consciousness in a subject. Such methods typically comprise 
detecting one or more brain wave forms and/or patterns or ratios in the 
subject and correlating such wave form(s), pattern(s), and/or ratio(s) 
with an alert or non-alert state of consciousness. 
Yet another aspect of this invention concerns methods for maintaining an 
alert state of consciousness through the use of a device according to the 
invention. Certain of these embodiments involve detecting a brain wave 
pattern in the subject and determining if the brain wave activity detected 
is indicative of an alert state of consciousness, and if not, stimulating 
the subject until brain activity indicative of an alert state of 
consciousness is detected. Yet other embodiments of this aspect concern 
determining if the subject is producing brain activity indicative of a 
non-alert state of consciousness and, if so, providing a stimulus, or 
series of stimuli, until an alert mental state is restored.

DETAILED DESCRIPTION OF THE INVENTION 
The present invention is based on the development of a device capable of 
monitoring the brain wave patterns of a subject wearing the device in 
order to determine when the subject transitions from an alert mental state 
of consciousness to a non-alert mental state. Upon detection of a 
transition from an alert to a non-alert state of consciousness, the device 
delivers a physical stimulus to the subject to restore the desired state 
of consciousness, i.e., an alert mental state, to the subject. 
As used herein, an "alert mental state" or "alert state of consciousness" 
shall refer to a mental state wherein the brain wave pattern of the 
subject is indicative of an alert mental state. Whether or not a subject 
is in an alert mental state can be determined by monitoring one or more 
brain waves, or brain wave patterns, alone or in combination with 
detecting physical manifestations of a non-alert mental state, e.g., eye 
blinks and jaw movement. In contrast, a "non-alert mental state" or 
"non-alert state of consciousness" shall be any mental state or level of 
consciousness other than an alert mental state. 
A brain wave pattern associated with an alert mental state is that which 
occurs in a subject when the subject is alert. Such a pattern may be based 
on an average obtained by analysis of the brain wave patterns of at least 
two subjects in an alert mental state when the pattern is monitored. 
Alternatively, such a brain wave pattern may be specific to the particular 
subject, and is preferably established by averaging the results obtained 
by monitoring the brain wave patterns of the subject at least twice while 
in an alert mental state. Such patterns may be initially established by 
monitoring brain wave patterns at the same time as other parameters 
indicative of an alert or non-alert mental state are also monitored. For 
example, detection of physical manifestations of a mental state can be 
using the device described in U.S. Pat. No. 5,626,145. When one or more 
physical manifestations of a non-alert mental state are detected, a brain 
wave pattern then occurring, or, preferably, which immediately preceded 
the physical manifestation, is recorded and used to establish the pattern 
indicative of a non-alert mental state. 
Alternatively, in a preferred embodiment of the invention, the brain wave 
pattern of a subject in an alert mental state and a non-alert mental 
state, and the transition from an alert to a non-alert mental state, are 
monitored while the subject performs a task the adequate performance of 
which requires an alert mental state. Such tasks may include manual 
dexterity testing, mathematical problem solving, reading comprehension 
tests, or any other vigilance test known in the art wherein optimal 
performance requires mental alertness. Preferably, the subject is well 
rested and free from illness at the time of such testing. A brain wave 
pattern associated with a non-alert state of consciousness is any brain 
pattern that is not associated with an alert mental state. As will be 
appreciated by those in the art, objective performance will be monitored 
over time, and as performance declines, brain patterns associated 
therewith will be recorded and used to establish the pattern indicative of 
a non-alert mental state. 
Because brain wave patterns associated with an alert state of consciousness 
may vary from subject to subject, or vary even in the same subject over 
time, it is preferred that the point determined to be that of the 
transition from an alert mental state to one of a non-alert state be such 
that at least about 50%, preferably at least about 75%, and more 
preferably, at least about 95% of the time such transition has in fact 
occurred. Typically, this is confirmed by the simultaneous or immediately 
subsequent (i.e., less than about 30 seconds, preferably less than about 
10, 5, 3, 2, 1, 0.5, or 0.1 seconds) occurrence of a physical 
manifestation associated with a non-alert mental state, although an 
objective decline in performance of a task requiring an alert mental state 
can also be used. 
In practicing this invention, it is important to monitor and analyze brain 
waves and/or brain wave patterns. Any monitor capable of measuring brain 
wave activity can be used. Examples of such monitors include EEGs. 
Brain waves which are preferably monitored in accordance with this 
invention include alpha, beta, theta, and delta waves. Of these, several 
correspond to different levels of sleep, such as alpha (exhibiting brain 
wave activity in the range of about 8 Hz to about 12 Hz, as monitored by 
EEG), theta (about 6 Hz to about 8 Hz, as monitored by EEG), and delta 
(about 1 Hz to about 4 Hz, as monitored by EEG). Brain waves exhibiting 
EEG-monitored frequencies from about 12 Hz to about 30 Hz, referred to as 
beta waves, are characteristic of an alert state of consciousness in an 
individual, though beta activity at even higher frequencies has been 
observed in different types of mental activities. Another brain wave, 
referred to as a gamma wave, may also be used in the practice of this 
invention. As used herein, gamma activity is characterized as all 
EEG-monitored brain activity above about 30 Hz. As those in the art will 
appreciate, the boundaries between gamma and beta, beta and alpha, alpha 
and theta, and theta and delta are somewhat arbitrary. Thus, the foregoing 
delineations are intended to be exemplary and not limiting. Furthermore, 
use of other brain wave types or classifications useful in distinguishing 
an alert mental state from a non-alert mental state, whether now known or 
later discovered, are within the scope of the invention. 
Of particular importance in the practice of the preferred embodiment of 
this invention is the determination of the ratio between alpha and beta 
brain waves detected over a particular time period, although ratios 
involving other brain wave forms can also be used in the practice of this 
invention, so long as one such form correlates with alert mental function 
and another correlates with non-alertness. As a subject becomes less 
alert, the level of alpha activity increases and the level of beta 
activity decreases, thus altering the alpha:beta ratio. When this ratio 
reaches a predetermined value (the "transition ratio"), i.e., that which 
has been determined to exist when the transition from an alert mental 
state to a non-alert state occurs, a physical stimulus is provided to 
restore an alert mental state. It is understood that as used herein, for 
convenience an "alpha" brain wave shall be considered any level of brain 
activity associated with a non-alert mental state, and thus in addition to 
brain waves having frequencies of about 8 Hz to about 12 Hz (as monitored 
by EEG), also includes theta, delta, and other brain waves having 
frequencies below those of beta waves. Similarly, for convenience, brain 
activity, including brain waves, associated with an alert state of 
consciousness are referred to herein as "beta" waves, and thus include 
waves having EEG-monitored frequencies from about 12 Hz to about 30 Hz and 
above. 
The alpha:beta ratio may be expressed in terms of alpha to beta 
("alpha:beta"), or beta to alpha ("beta:alpha"), which ratio is preferably 
calculated over consecutive periods ranging from less than about one 
second, from about 1 to about 5 seconds, from about 5 to about 10 seconds, 
and from about 10 to about 30 seconds or more. As those in the art will 
appreciate, because a microprocessor-based device according to the 
invention will enable alpha:beta ratios to be determined over almost any 
interval, the foregoing discussion of intervals is merely advisory, and 
the selection of a particular interval is left to the skilled artisan. 
As those in the art will appreciate, alpha:beta transition ratios can be 
determined in various ways, and can be generic (i.e., as a preset value 
programmed into a device according hereto based upon analysis of one or 
more subjects other than the subject wearing the device) or individualized 
(i.e., determined specifically for an individual user). One way in which 
the alpha:beta transition ratio can be determined is to monitor 
(preferably continuously) alpha and beta wave activity in one or more well 
rested subjects during an activity requiring a high level of 
consciousness, e.g., reading, interactive games, etc., until such time as 
one or more manifestations, including physical manifestations (e.g., 
eyelid, jaw, and/or head movement), of a non-alert mental state are 
detected. In such instances, the alpha:beta transition ratio is that which 
is calculated to exist at the time the first manifestation(s) of a 
non-alert mental state is(are) detected. Alternatively, the alpha:beta 
transition ratio may be determined by calculating the ratio at some time 
prior to the occurrence of any such physical manifestation(s)(the 
"pre-transition period"). Preferred pre-transition periods are those from 
about 0.001 seconds to about 100 seconds before any physical manifestation 
of a non-alert mental state occur or is detectable. Of course, 
pre-transition periods of shorter or longer duration can also be used. In 
preferred embodiments of the invention, the alpha:beta transition ratio is 
a value calculated to occur prior to any physical manifestation of a 
non-alert mental state. The actual length of the pre-transition period 
desired is best left to the skilled artisan depending upon the particular 
application. 
Numerous devices are currently available to detect brain wave patterns, 
including electroencephalographs and magnetoencephalographs. These and 
similar devices typically employ one or more brain wave sensors, 
preferably electrodes, placed in physical contact with a portion of a 
subject's scalp in order to detect brain wave impulses. As those in the 
art will appreciate, any brain wave sensor capable of monitoring or 
detecting brain waves can be adapted for use in the practice of this 
invention. Usually, the monitoring sensors attached to a patient are 
operably connected via cables or wires (e.g., leads) to a distal 
physiological monitoring instrument, which may or may not itself include a 
computer. One example of such a physiological monitoring instrument is the 
I-330 DSP-12 system (J & J Engineering, Inc., Poulsbo Wash.). 
Any portion of the patient's body from which brain waves can be detected 
can be used as a contact area for a brain wave sensor. In preferred 
embodiments of the invention, the device will employ at least two sensing 
electrodes, each of which makes contact with the skin of subject's head, 
preferably with the subject's scalp. For convenience, the electrodes (or 
other brain wave sensor(s)) are connected to, and preferably carried in, a 
hat, headband, eyeglass frame, or other piece of headgear which can be 
comfortably worn on a user's head for extended periods. Preferred areas 
for electrode placement are depicted in FIG. 2. When two or more brain 
wave sensors are employed in a device according to the invention, it is 
preferred that the sensors be positioned such that when a sensor is 
positioned to contact a particular portion of the scalp on one side of the 
subject's head (see FIG. 2), another sensor is positioned to contact a 
substantially corresponding region on the other side of the subject's 
head. 
Brain wave data from the brain wave sensor(s) is transmitted to the 
components) which then digitizes, if necessary, and analyzes the data, 
and, if necessary, provides notification or an alarm (or other stimulus) 
to the subject (typically through a perceptible physical stimulus) that a 
non-alert mental state exists or is imminent. 
In preferred embodiments of the invention, the data gathered by the brain 
wave sensor(s) is transmitted to a digital processor housed in the same 
unit which carries the electrode. However, the processor may be located 
more remotely, and data can be transmitted thereto by conventional means, 
for instance, by an appropriate cable or wire loom. In addition, the 
invention envisions transmission of brain wave data to a remote processor 
via radio, radiotelephone, or other wireless transmission or other similar 
means for sending and receiving telemetry. In the event telemetry is 
employed, the data transmitter can be proximate or distal to the brain 
wave sensors. If distally located, again the transmitter would be 
connected to the sensor(s) via a cable or similar means. Data may be 
transmitted in either analog or digital form. 
Upon receipt of the brain wave data from the sensor(s), it is then analyzed 
by a processor, preferably a small digital computer or microprocessor. If 
the data from the brain wave sensors is transmitted to the processor in 
analog form, it will first be converted to a digital form prior to 
processing. In preferred embodiments of the invention, prior to or as part 
of the processing function, the brain wave data is filtered to remove 
information not required for determining whether an alert or non-alert 
mental state exists in the subject whose brain waves are being monitored. 
Filters which remove brain waves of particular frequencies are known in 
the art, and one or more such filters can be employed. In addition, it may 
be desirable to filter out "noise" or other non-brain wave data included 
in that which is transmitted from the sensors. Methods and components for 
accomplishing such filtering are known in the art. For example, see U.S. 
Pat. No. 5,626,145. 
The processor will typically then separate the brain wave data into data 
sets representing the various brain waves to be analyzed. For example, if 
only alpha and beta waves are to be analyzed, this information will be 
discerned from the incoming data, unless, of course, brain wave sensors 
specific for only a specific type of brain wave are employed, or the 
sensor data is preprocessed or filtered prior to its arrival at the 
processor, making the foregoing unnecessary. After producing the desired 
data sets, it is analyzed to determine if the data is indicative of an 
alert mental state. If so, nothing more need be done with such data, 
although, if desired, it may be saved to an associated storage device. 
Data so stored may be used for different purposes, such as to analyze when 
the transition from an alert to a non-alert mental state occurred. Such 
information would be useful in analyzing the causes of accidents, the 
effectiveness of the teaching regimen being employed (as it relates to 
keeping observers mentally alert), etc. 
If, on the other hand, the data indicate that a non-alert mental state 
exists or is imminent, the processor activates an alarm or other 
notification system operably connected thereto (or otherwise associated 
therewith in an operable fashion) to inform the subject of the existing or 
imminent non-alert mental state in order to restore an alert mental state. 
In preferred embodiments of the invention, the alarm is a perceptible 
physical stimulus, for example, a sound (or series thereof), light, 
pressure, vibration, shock or other electrical stimulus, or a combination 
of two or more different stimuli. Particularly preferred are auditory 
alarms based on sound. The sound may be a single frequency or multiple 
frequencies, and provided in simultaneous or consecutive fashion, and is 
preferably emitted by one or more speakers or other sound generators 
positioned in or adjacent to one or both ear canals of the subject. The 
alarm stimulus may be continuously or intermittently administered until an 
alert state of consciousness is restored, as monitored by the device. The 
amplitude or intensity of the alarm stimulus preferably should be 
sufficient to produce a transition from a non-alert to an alert mental 
state as rapidly as possible but without startling or upsetting the 
subject, which intensity may progressively increase until the desired 
mental state is restored. In particularly preferred embodiments, a device 
according hereto will contain a menu of alarm stimuli from which a 
particular subject can choose. Alternatively, in other embodiments the 
device is configured so that the user can select the stimuli to be 
employed, if necessary to restore an alert mental state. 
In addition to the foregoing, the device may contain data transmission, 
reception, and/or other telemetry capability, such that the mental state 
of the subject wearing the device can be remotely monitored. 
In preferred embodiments, the device according to the invention is one 
which, in addition to being capable of monitoring and restoring an alert 
mental state, can also "learn" or adapt to what constitutes a transition 
from an alert mental state to a non-alert mental state in a user of the 
device. As such, the device can be used at different times by multiple 
subjects, while at the same time being "customized" to the brain wave 
patterns of a particular user. To accomplish this, the device incorporates 
the software necessary to assess brain wave(s), patterns, and/or ratios 
associated with alert and non-alert mental states in a given subject. Of 
course, this capability could alternatively, or additionally, be included 
in a compatible device that downloads or otherwise transfers such 
information to a device according to the invention. Making this assessment 
enables the device to establish the transition ratio which, when reached, 
results in the alarm being activated. 
A device according to the invention that is capable of "learning" 
preferably also contains, or is associated with a storage device that 
contains, a library of brain wave patterns and/or transition ratios stored 
in memory. Such a library may be specific to a given subject, or include 
information from multiple subjects. In this way, it is unnecessary for the 
device to "relearn" what constitutes a brain wave pattern or transition 
ratio for a given subject. Of course such information could be stored in a 
storage system incorporated into the device or be downloaded into the 
device, as circumstances dictate. 
In order for the devices according to the invention to function, a supply 
of electricity is required. The particular specifications of the electric 
power supply employed will depend on the power requirements of the 
particular device, and thus this selection is left to the artisan. 
However, power supplies useful in the practice of this invention will 
include those that can be incorporated into the device, and are preferably 
portable and removable or detachable. Preferred power supplies include 
batteries and solar cells, although in many applications, it is acceptable 
to draw power from an external source, e.g., the electrical system of a 
truck or other form of transportation. 
As is apparent from the above, devices such as those disclosed herein can 
be used to monitor whether or not an alert mental state exists in a 
subject wearing such a device, and if not, to restore the desired mental 
state, i.e., an alert state of consciousness, through stimulation of the 
subject by an appropriate stimulus. The devices and methods disclosed 
herein will find application in many fields, for example, in the 
transportation industry (e.g., automobile and truck drivers, pilots (of 
aircraft and watercraft), air traffic controllers, military personnel, and 
train engineers. In addition, these devices and methods will find use in 
any application where maintenance of an alert mental state is important, 
for example, amongst judges and jurors in the civil and criminal justice 
systems, students observing lectures, and pursuits involving hazardous 
activities or dangerous machinery. Devices such as those disclosed herein 
which contain data logging or telemetry capability will also be useful in 
many fields, for example, in the development of teaching techniques which 
promote prolonged periods of alertness. In such circumstances, it may be 
desirable to use a device according to the invention that partially or 
completely lacks the capability, whether by design or deactivation, to 
provide restorative stimuli in response to a detected non-alert mental 
state. 
As those in the art will appreciate, the foregoing description is merely 
illustrative of preferred embodiments of the invention, and is not 
limiting in any way. Moreover, upon reading the foregoing, many 
alternative embodiments of the invention will become apparent to those 
skilled in the art, each of which shall be considered within the scope 
hereof. 
Each of the documents discussed herein is hereby incorporated by reference 
in its entirety, and any such discussion shall not constitute an admission 
as to whether or not any such reference is prior art.