Examining the Biological Factors That Affect Sleep Duration
Condition: Sleep; Circadian Rhythm; Cognitive Performance
Study type: Observational

Summary: 
      Sleep is necessary for healthy functioning, and people who sleep too little or too much may
      have an increased risk of developing health problems. This study will examine people who
      regularly sleep for short or long amounts of time to understand the biological factors that
      determine how much sleep a person needs.
    

Detailed description: 
      The amount of sleep people require depends on many factors, including age, but experts agree
      that most adults need 7 to 8 hours of sleep a night. People who sleep for shorter or longer
      amounts of time may be at risk of developing memory problems, heart disease, obesity, and
      diabetes. The duration and timing of sleep are regulated by an interaction between the
      circadian pacemaker, or biological clock, and the sleep homeostat, which is an internal
      account of the amount of sleep a person has received recently. It is unknown whether there is
      a biological or genetic basis for the amount of sleep a person needs. This inpatient study
      will examine two extreme sleep groups: short sleepers who sleep 6.5 or less hours a night and
      long sleepers who sleep 9 or more hours a night. Participants will be exposed to identical
      sleep opportunities and living conditions. Using hormone analysis to examine participants'
      circadian rhythms, researchers will evaluate the biological differences that people undergo
      during the sleep process. Results from this study may help researchers understand whether
      sleep duration and sleep needs differ among people because of biological and genetic
      variations.

      Over a period of 4 to 6 weeks, potential study participants will attend 4 to 6 screening
      visits, which will include a medical history review, physical exam, blood and urine
      collection, electrocardiogram (EKG) to measure electrical activity of the heart, a
      psychological assessment, and an overnight stay in a sleep laboratory. For 3 weeks, potential
      participants will also wear an activity monitor, and they will record sleep habits
      electronically and in a daily diary.

      Participants who are eligible for the study will spend 28 days in the Intensive Physiological
      Monitoring Unit of the Clinical and Translational Sciences Center at the Brigham and Women's
      Hospital. Participants will not have access to a clock, radio, television, or computer, and
      they will not be allowed any outside contact. Most days participants will remain in bed for
      10 to 14 hours; however, at selected times during the study, participants will remain
      inactive for periods of 32 to 64 hours and will stay awake for 32 to 40 hours. Throughout the
      study, participants' sleep patterns will be monitored continuously by a wrist activity
      recorder. Heart rhythms, brain electrical activity, eye movements, and temperature will also
      be measured continuously. At different times throughout the study, participants will undergo
      urine, saliva, and blood collection; alertness, mood, and performance evaluations; and blood
      pressure measurements. Upon release from the research center, participants will maintain a
      sleep diary for 3 weeks.
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Participants will include healthy people who are catagorized as either short sleepers or
        long sleepers.
      
Biospecimen description: 
      Plasma samples
    
Keywords: Basic Research; Individual Sleep Duration; Melatonin; Electroencephalogram; Alertness; Mood