Neurobehavioral Impact of Successive Cycles of Sleep Restriction With and Without Naps in Adolescents

Abstract

Study Objectives:To characterize adolescents’ neurobehavioral changes during two cycles of restricted and recovery sleep and to examine the effectiveness of afternoon naps in ameliorating neurobehavioral deficits associated with multiple nights of sleep restriction.Methods:Fifty-seven healthy adolescents (aged 15–19 years; 31 males) participated in a parallel group study. They underwent two cycles of sleep restriction (5-hr time in bed [TIB] for five and three nights in the first and the second cycles, respectively; 01:00–06:00) and recovery (9-hr TIB for two nights per cycle; 23:00–08:00) intended to simulate the weekday sleep loss and weekend attempt to “catch up” on sleep. Half of the participants received a 1-hr nap opportunity at 14:00 following each sleep-restricted night, while the other half stayed awake. Sustained attention, sleepiness, speed of processing, executive function, and mood were assessed 3 times each day.Results:Participants who were not allowed to nap showed progressive decline in sustained attention that did not return to baseline after two nights of recovery sleep. Exposure to the second period of sleep restriction increased the rate of vigilance deterioration. Similar patterns were found for other neurobehavioral measures. Napping attenuated but did not eliminate performance decline. These findings contrasted with the stable performance of adolescents, given 9-hr TIB each night in our recent study.Conclusions:Adolescents’ neurobehavioral functions may not adapt to successive cycles of sleep curtailment and recovery. In sleep-restricted adolescents, weekend “catch-up sleep,” even when combined with napping during weekdays, is inferior to receiving a 9-hr sleep opportunity each night.

Assessing the benefits of napping and short rest breaks on processing speed in sleep‐restricted adolescents

“…Details of the nap durations are reported in Lo et al . (). In brief, PSG assessment showed that the nap group slept 37–53 min more than the no‐nap group each day ( P < 0.001), incurring a lower sleep debt over the course of the protocol.…”

“…Details of this protocol are reported in Lo et al . (). The protocol for this study was approved by the Institutional Review Board of the National University of Singapore, and all participants signed written informed consent.…”

Trait‐like characteristics of sleep EEG power spectra in adolescents across sleep opportunity manipulations

“…Data were acquired from adolescents participating in two protocols – the Need for Sleep Studies (NFS) 1 and 2 (Lo, Ong, Leong, Gooley, & Chee, ; Lo et al., ; Ong, Lo, Gooley, & Chee, , ). Participants met the following screening criteria: (i) between 15 and 19 years old; (ii) no history of chronic medical conditions, psychiatric illness or sleep disorders; (iii) a body mass index (BMI) of ≤ 30 kg m −2 ; (4) not habitual short sleepers (i.e.…”

“…not individuals who both [a] had an average actigraphically assessed TIB of < 6 hr; and [b] showed no sign of sleep extension for more than 1 hr on weekend compared with weekday nights); (v) daily consumption of fewer than five cups of caffeinated beverages; and (vi) no history of travel across more than two time zones 1 month prior to the experiment. Full details of the recruitment and screening criteria are detailed in our earlier work (Lo et al., , ). The study was approved by the Institutional Review Board of the National University of Singapore, and informed consent was obtained from both participants and their legal guardian.…”

“…The present work seeks to determine if such “trait‐likeness” of the sleep EEG persists across sleep restriction, naps and recovery nights in adolescents who typically shorten sleep on weeknights and compensate by taking daytime naps or extending sleep on weekends (Gradisar, Wright, Robinson, Paine, & Gamble, ; Lo et al., ). Work to date has shown high within‐ compared with between‐subject correlations across baseline, slow‐wave sleep deprivation and recovery nights of equal time‐in‐bed (TIB; De Gennaro et al., ; Tarokh et al., ).…”