Clinical trial NCT02838095: Effects of Napping in Sleep-Restricted Adolescents
Official title: Effectiveness of a Daytime Nap on Alleviating Cognitive Impairment Due to Short Sleep in Adolescents
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Sleep Deprivation
Sleep
Keywords: nap
sleep restriction
recovery sleep
cognitive performance
subjective sleepiness
mood
neurobehavioural functions
Lead sponsor: Duke-NUS Graduate Medical School
Sponsor class: OTHER
Collaborators: name: National Medical Research Council (NMRC), Singapore
First posted: 2016-07-20
Enrollment: 57
Sex: ALL
Minimum age (years): 15
Maximum age (years): 19
Standard ages: CHILD
ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: PARALLEL
Primary purpose: BASIC_SCIENCE

Brief summary: To examine the neurobehavioural responses to two successive cycles of sleep restriction and recovery in adolescents, and to determine the benefits of napping on cognitive performance, alertness, and mood. 57 participants, aged 15 to 19 years old, were divided into nap and no-nap groups. Both groups underwent two cycles of sleep restriction and recovery over 15 days. The nap group received an afternoon sleep opportunity lasting 1 hour.

Detailed description: 57 participants (aged 15 to 19 years old) were grouped into nap and no nap groups. Both groups took part in a 15-day protocol that started with 2 9-hour adaptation and baseline nights, followed by two successive cycles of sleep restriction (5-h time-in-bed \[TIB\]; 01:00-06:00) and recovery (9-h TIB; 23:00-08:00) intended to simulate the weekday sleep loss and weekend attempt to 'catch up' that are familiar to high school students. The nap group received a 1-hour nap opportunity at 14:00 following each sleep-restricted night, while participants in the no nap group watched a documentary. Sleep was monitored with polysomnography on 9 selected nights. Cognitive performance, subjective sleepiness, and mood were assessed 3 times daily (10:00, 15:45, and 20:00).

All participants stayed in air-conditioned, twin-share bedrooms with en-suite bathrooms. Bedroom windows were fitted with blackout panels to ensure participants were not woken up prematurely by sunlight. Earplugs were also provided, and participants were allowed to adjust the temperature of their bedrooms to their personal comfort. 3 main meals were served each day, with snacks being provided for upon request. Caffeinated drinks, unscheduled sleep, and strenuous physical activities were prohibited.

Outside of scheduled sleep, meal, and cognitive testing times, participants spent the majority of their free time in a common room that was illuminated by natural and artificial lighting. They were allowed to read, play non-physically exerting games, watch videos, and interact with research staff and other participants. Participants were under constant supervision by the research staff.

Eligibility criteria: Inclusion Criteria:

* healthy
* no sleep disorder
* body mass index not greater than 30

Exclusion Criteria:

* smoker
* habitual short sleeper (time in bed during term time of less than 6 hours and no sign of sleep extension of greater than 1 hour on weekends)
* consumption of more than 5 cups of caffeinated beverages a day
* travelling across more than 2 time zones in the month prior to the study protocol
* diagnosed with any psychiatric conditions

Primary outcomes:
measure: 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: 3 times daily (10:00, 15:45, and 20:00) for 15 days
measure: Change in working memory assessed with the 1-back task from morning to afternoon and then evening from baseline days to the first and second cycles of sleep restriction and recovery
timeFrame: 3 times daily (10:00, 15:45, and 20:00) for 15 days
measure: Change in executive functions assessed with the 3-back task from morning to afternoon and then evening from baseline days to the first and second cycles of sleep restriction and recovery
timeFrame: 3 times daily (10:00, 15:45, and 20:00) for 15 days
measure: Change in the level of subjective sleepiness assessed with the Karolinska Sleepiness Scale from morning to afternoon and then evening from baseline days to the first and second cycles of sleep restriction and recovery
timeFrame: 3 times daily (10:00, 15:45, and 20:00) for 15 days
measure: 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 restriction and recovery
timeFrame: 3 times daily (10:00, 15:45, and 20:00) for 15 days
measure: 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 restriction and recovery
timeFrame: 3 times daily (10:00, 15:45, and 20:00) for 15 days
measure: Change in speed of processing assessed with the Mental Arithmetic Task from morning to afternoon and then evening from baseline days to the first and second cycles of sleep restriction and recovery
timeFrame: 3 times daily (10:00, 15:45, and 20:00) for 15 days
measure: Change in speed of processing assessed with the Symbol Digit Modalities Task from morning to afternoon and then evening from baseline days to the first and second cycles of sleep restriction and recovery
timeFrame: 3 times daily (10:00, 15:45, and 20:00) for 15 days
Secondary outcomes:
measure: Change in total sleep duration at night assessed with polysomnography from baseline nights to the first and second cycles of sleep restriction and recovery
timeFrame: Nocturnal sleep on nights 1 & 3 (baseline), 4, 6 & 8 (first sleep restriction period), 9 (first recovery period), 11 & 13 (second sleep restriction period), & 14 (second recovery period)
measure: Change in N1 sleep duration at night assessed with polysomnography from baseline nights to the first and second cycles of sleep restriction and recovery
timeFrame: Nocturnal sleep on nights 1 & 3 (baseline), 4, 6 & 8 (first sleep restriction period), 9 (first recovery period), 11 & 13 (second sleep restriction period), & 14 (second recovery period)
measure: Change in N2 sleep duration at night assessed with polysomnography from baseline nights to the first and second cycles of sleep restriction and recovery
timeFrame: Nocturnal sleep on nights 1 & 3 (baseline), 4, 6 & 8 (first sleep restriction period), 9 (first recovery period), 11 & 13 (second sleep restriction period), & 14 (second recovery period)
measure: Change in N3 sleep duration at night assessed with polysomnography from baseline nights to the first and second cycles of sleep restriction and recovery
timeFrame: Nocturnal sleep on nights 1 & 3 (baseline), 4, 6 & 8 (first sleep restriction period), 9 (first recovery period), 11 & 13 (second sleep restriction period), & 14 (second recovery period)
measure: Change in REM sleep duration at night assessed with polysomnography from baseline nights to the first and second cycles of sleep restriction and recovery
timeFrame: Nocturnal sleep on nights 1 & 3 (baseline), 4, 6 & 8 (first sleep restriction period), 9 (first recovery period), 11 & 13 (second sleep restriction period), & 14 (second recovery period)
measure: Change in total sleep duration during daytime naps assessed with polysomnography from the first to the second sleep restriction period
timeFrame: Afternoon naps on days 4, 6 & 8 (first sleep restriction period), 11 & 13 (second sleep restriction period)
measure: Change in N1 sleep duration during daytime naps assessed with polysomnography from the first to the second sleep restriction period
timeFrame: Afternoon naps on days 4, 6 & 8 (first sleep restriction period), 11 & 13 (second sleep restriction period)
measure: Change in N2 sleep duration during daytime naps assessed with polysomnography from the first to the second sleep restriction period
timeFrame: Afternoon naps on days 4, 6 & 8 (first sleep restriction period), 11 & 13 (second sleep restriction period)
measure: Change in N3 sleep duration during daytime naps assessed with polysomnography from the first to the second sleep restriction period
timeFrame: Afternoon naps on days 4, 6 & 8 (first sleep restriction period), 11 & 13 (second sleep restriction period)
measure: Change in REM sleep duration during daytime naps assessed with polysomnography from the first to the second sleep restriction period
timeFrame: Afternoon naps on days 4, 6 & 8 (first sleep restriction period), 11 & 13 (second sleep restriction period)
Other outcomes:
Locations:
city: Singapore
country: Singapore
facility: Duke-NUS Medical School
Study officials:
affiliation: Duke-NUS Graduate Medical School
name: Michael WL Chee, MBBS
role: PRINCIPAL_INVESTIGATOR
References:
citation: Lo JC, Koa TB, Ong JL, Gooley JJ, Chee MWL. Staying vigilant during recurrent sleep restriction: dose-response effects of time-in-bed and benefits of daytime napping. Sleep. 2022 Apr 11;45(4):zsac023. doi: 10.1093/sleep/zsac023.