Sleep Timing on Energy Intake and Energy Expenditure
Condition: Obesity
Study type: Interventional

Summary: 
      Studies in healthy young adults have shown that abnormal and undesirable physiological
      changes are a result of chronic sleep curtailment, with implications on inflammatory status,
      blood glucose regulation, circulating free fatty acids, and insulin sensitivity.
      Epidemiological studies suggest an increase in energy intake with shortened, sleep and this
      has been associated with weight gain. Interestingly most studies examining sleep restriction
      do not consider whether the restricted sleep is due to sleep delay or an advanced wake time.
      This study will investigate the change in physical activity or food intake during a period of
      sleep restriction. To date only one study has addressed this question but they only examined
      one study night and followed their subjects for only 24 hr. The objective of the proposed
      project is to examine the effects of shortened sleep on potential changes in physical
      activity and energy intake.

      The investigators hypothesize that after several nights of short sleep that different
      strategies are employed to remain awake and these strategies will also vary whether bed time
      was delayed or wake time was advanced.

      Aim 1: To examine the effects of sleep timing on energy intake and expenditure during periods
      of sleep restriction
    

Detailed description: 
      Subjects will have preliminary screening tests. There will be 3 study conditions, with the
      latter 2 conditions (delayed bed time/advanced wake time) will be completed in a randomized,
      crossover design. Subjects will wear an activity monitor (actigraph) and sleep monitor
      (actiwatch) for 6 days. Dietary records and smart phones will be used record energy intake.

      For the first experimental condition, the subject will wear the actiwatch and actigraph, and
      monitor food intake for 6 day of normal sleep. This condition will allow determination of
      their sleep pattern and when they habitually go to bed (ie. 11 pm - 5 am) and awaken.

      On the second condition, the investigators will allow subjects to maintain their usual
      physical activity and dietary patterns but the investigators will ask subjects to delay the
      time of going to bed by 2 hr. Subjects will be followed for 4 nights of shortened sleep but
      data will be collected for 6 days. On the other condition, subjects will go to bed at the
      usual time but awaken 2 hr earlier that they normally would. Again subjects will monitor
      their physical activity, hunger/fullness, sleep and energy intake. These latter 2 conditions
      will be randomized.

      Visit 1: Subjects will be provided a verbal explanation of the study and will sign the
      informed consent if interested. Subjects will then complete questionnaires assessing health
      history, sleep, morningness and physical activity habits.

      Visit 2: Subjects will collect physical activity monitor (actigraph) and sleep monitor
      (actiwatch) along with surveys to fill out each day about dietary consumption, sleep habits
      and physical activity, lasting for 6 days. Subjects will also be asked to photograph any food
      or drink they consume.

      Visit 3: Return the actiwatch and actigraph.

      Visit 4-5: Repeat of Visit 2-3.

      Visit 6-7: Repeat of Visit 2-3.
    

Intervention name(s): Delayed bedtime sleep restriction; Early wake sleep restriction
Intervention type(s): Behavioral; Behavioral
Intervention description(s): bedtime 2 hr later than their normal bedtime; wake time 2 hr earlier than their normal wake time
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: All subjects will complete 3 study conditions with a minimum of one week between each condition.
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: sleep restriction; physical activity; dietary intake; insulin resistance