This proposed project will investigate whether a variable or a stable sleep schedule will be more effective in minimizing neurobehavioural and metabolic deficits when total sleep opportunity across two weeks is below the recommended sleep duration. In this laboratory-based, stay-in study, 60 young adults will be randomized into 1 of 3 groups. After 2 nights of 8-h time-in-bed (TIB) that simulate longer sleep opportunities typical of weekends, the stable short sleep group will have a 6-h TIB in each of the following 5 'weeknights' (8866666). The variable short sleep group (8884846) will also have a total TIB of 30h during the 'weeknights', although TIB varies across the 'weeknights'. The nightly TIB of the well-rested control group will be 8h (8888888). These manipulations will repeat in the second week, enabling the tracking of outcome measures during recurrent weeks of sleep restriction on 'weekdays' and extension on 'weekends'. A test battery assessing basic cognitive functions and mood will be administered 5 times a day. A long-term memory encoding task will be administered after week 1. A functional Magnetic Resonance Imaging (fMRI) brain scan, and an Oral Glucose Tolerance Test (OGTT) will be conducted after the second 'weekend' night and after the last 'weeknight' each week. Continuous glucose monitoring will be conducted throughout the experiment. Sleep will be measured every night with polysomnography.
Age range
21 Years – 35 Years
Sex
ALL
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Change in sustained attention assessed with the Psychomotor Vigilance Task from morning to afternoon and then evening from baseline days to the first and second cycles of sleep restriction and recovery
Timeframe: 5 times daily for 16 days
Change in mean reaction time assessed with the Psychomotor Vigilance Task from morning to afternoon and then evening from baseline days to the first and second cycles of sleep restriction and recovery
Timeframe: 5 times daily for 16 days
Change in median reaction time assessed with the Psychomotor Vigilance Task from morning to afternoon and then evening from baseline days to the first and second cycles of sleep restriction and recovery
Timeframe: 5 times daily for 16 days
Change in standard deviation in reaction time of sleep restriction and recovery
Timeframe: 5 times daily for 16 days
Change in number of commission errors / false starts assessed with the Psychomotor Vigilance Task from morning to afternoon and then evening from baseline days to the first and second cycles of sleep restriction and recovery
Timeframe: 5 times daily for 16 days
Change in number of correct matches assessed with the 1-back task from morning to afternoon and then evening from baseline days to the first and second cycles of sleep manipulation and recovery
Timeframe: 5 times daily for 16 days
Change in number of correct mismatches assessed with the1-back task from morning to afternoon and then evening from baseline days to the first and second cycles of sleep manipulation and recovery
Timeframe: 5 times daily for 16 days
Change in number of incorrect matches assessed with the1-back task from morning to afternoon and then evening from baseline days to the first and second cycles of sleep manipulation and recovery
Timeframe: 5 times daily for 16 days
Change in incorrect mismatches assessed with the1-back task from morning to afternoon and then evening from baseline days to the first and second cycles of sleep manipulation and recovery
Timeframe: 5 times daily for 16 days
Change in discriminability measure (A') assessed with the1-back task from morning to afternoon and then evening from baseline days to the first and second cycles of sleep manipulation and recovery
Timeframe: 5 times daily for 16 days
Change in bias measure (B"D) assessed with the1-back task from morning to afternoon and then evening from baseline days to the first and second cycles of sleep manipulation and recovery
Timeframe: 5 times daily for 16 days
Change in number of correct matches assessed with the 3-back task from morning to afternoon and then evening from baseline days to the first and second cycles of sleep manipulation and recovery
Timeframe: 5 times daily for 16 days
Change in number of correct mismatches assessed with the 3-back task from morning to afternoon and then evening from baseline days to the first and second cycles of sleep manipulation and recovery
Timeframe: 5 times daily for 16 days
Change in number of incorrect matches assessed with the 3-back task from morning to afternoon and then evening from baseline days to the first and second cycles of sleep manipulation and recovery
Timeframe: 5 times daily for 16 days
Change in number of incorrect mismatches assessed with the 3-back task from morning to afternoon and then evening from baseline days to the first and second cycles of sleep manipulation and recovery
Timeframe: 5 times daily for 16 days
Change in discriminability measure (A') assessed with the 3-back task from morning to afternoon and then evening from baseline days to the first and second cycles of sleep manipulation and recovery
Timeframe: 5 times daily for 16 days
Change in bias measure (B"D) assessed with the 3-back task from morning to afternoon and then evening from baseline days to the first and second cycles of sleep manipulation and recovery
Timeframe: 5 times daily for 16 days
Change in the level of subjective sleepiness assessed with the Karolinska Sleepiness Scale from morning to afternoon then evening from baseline days to the first and second cycle of sleep manipulation and recovery
Timeframe: 5 times daily for 16 days
Change in positive mood assessed with the Positive and Negative Affect Scale (PANAS) from morning to afternoon and then evening from baseline days to the first and second cycles of sleep manipulation and recovery
Timeframe: 5 times daily for 16 days
Change in negative mood assessed with the Positive and Negative Affect Scale (PANAS) from morning to afternoon and then evening from baseline days to the first and second cycles of sleep manipulation and recovery
Timeframe: 5 times daily for 16 days
Change in the level of depressive symptomatology from the mornings of the second baseline day to the last day of the first sleep manipulation cycle and the last day of the second sleep manipulation cycle.
Timeframe: 3 separate days (Day 3, 8 and 15)
Change in the level of anxiety symptomatology from the mornings of the second baseline day to the last day of the first sleep manipulation cycle and the last day of the second sleep manipulation cycle.
Timeframe: 3 separate days (Day 3, 8 and 15)
Change in the level of satisfaction with life from morning to afternoon and then evening from baseline days to the first and second cycles of sleep manipulation and recovery
Timeframe: 5 times daily (09:00, 12:00, 15:00, 18:00, 21:00) for 16 days
Change in speed of processing assessed with the Mental Arithmetic Test (MAT) from morning to afternoon and then evening from baseline days to the first and second cycles of sleep manipulation and recovery
Timeframe: 5 times daily (09:00, 12:00, 15:00, 18:00, 21:00) for 16 days
Change in speed of processing assessed with the Symbol Digit Modalities Test from morning to afternoon and then evening from baseline days to the first and second cycles of sleep manipulation and recovery
Timeframe: 5 times daily (09:00, 12:00, 15:00, 18:00, 21:00) for 16 days
Changes in the blood glucose levels from morning of the second baseline day to the last day of the first sleep manipulation cycle and the last day of the second sleep manipulation cycle.
Timeframe: 3 days (Day 3, 8 and 15) 6mL blood sample collection at 15, 30, 60, and 120 minutes
Changes in the insulin levels from morning of the second baseline day to the last day of the first sleep manipulation cycle and the last day of the second sleep manipulation cycle.
Timeframe: 3 days (Day 3, 8 and 15) 6mL blood sample collection at 15, 30, 60, and 120 minutes
Changes in interstitial fluid glucose levels from morning to afternoon then evening from baseline days to the first and second cycles of sleep manipulation and recovery.
Timeframe: All 16-days with 8-hour interval readings
Changes in the task related brain functional connectivity from the second baseline day to the last day of the first sleep manipulation cycle and the last day of the second sleep manipulation cycle.
Timeframe: 3 days (Day 3, 8, 15)
Changes in the resting-state brain functional connectivity from the second baseline day to the last day of the first sleep manipulation cycle and the last day of the second sleep manipulation cycle.
Timeframe: 3 days (Day 3, 8, 15)
Effect of variable sleep on picture encoding response time
Timeframe: Single session (Day 8)
Effect of variable sleep on picture encoding response accuracy
Timeframe: Single session (Day 8)
Effect of variable sleep on picture recognition response time
Timeframe: Single session (Day 10)
Effect of variable sleep on picture recognition hit rate
Timeframe: Single session (Day 10)
Effect of variable sleep on picture recognition false alarm rate
Timeframe: Single session (Day 10)
Effect of variable sleep on picture recognition discriminability measure (A')
Timeframe: Single session (Day 10)