AsianScientist (Jul. 11, 2019) – Feeling groggy and unfocused from running low on sleep is a relatable experience. While sleeping in on weekends or turning in early on some weekdays can feel like a lifesaver, it doesn’t fully restore our brains’ performance, according to a new study by researchers at National University of Singapore (NUS) published in Sleep.
Sleep-deprivation is known to take a toll on neurobehavioral functions such as processing information, sustaining attention, memory and emotional regulation. In their previous experiments in adolescents, the authors found that these deficits worsened over repeated cycles of weekday sleep restrictions, even when followed by weekend recovery sleep. Interestingly, another four-night study on adults revealed that mixing in some nights with more sleep helped participants stay more alert and think faster compared to maintaining a consistently short sleep schedule.
Due to conflicting evidence, the benefits of a variable short sleep schedule during weekdays are still debatable. Additionally, it’s unclear how multiple cycles of weekday sleep restraints and weekend lie-ins impact adults.
To put these uncertainties to rest, the NUS research team randomly assigned 52 healthy individuals, aged 21 to 35 years, into one of three groups: the stable short sleep group, the variable short sleep group and the control group.
The 16-day study included two cycles of a five-night sleep manipulation period and one to two nights of recovery sleep. Except for ‘weekends’ when all participants received an 8-hour shut-eye, the stable short sleep group slept for six hours on the five ‘weekdays’. Meanwhile the variable short sleep group had an 8-hour, 4-hour, 8-hour, 4-hour, and 6-hour bedtime from the first to the fifth night.
The control group maintained a consistent eight-hour sleep schedule throughout. Participants completed a computerized test five times daily to assess neurobehavioral functions.
Compared to the well-rested adults, both restricted sleep groups performed worse on cognitive tests. While repeated cycles of inadequate sleep deteriorated vigilance, incorporating night-to-night variability helped reduce these deficits. However, a variable sleep schedule did not protect against the lapses in processing speed and memory task performance.
Given the minimal deficits in working memory and executive functions in the variable short sleep group, along with contradicting literature on its benefits for vigilance, the authors recommended using different tasks and scales to better understand the impact of varying bedtimes for individuals getting inadequate sleep.
These findings suggest that while catching up on sleep for a few nights could blunt the negative effects of recurrent sleep restrictions, it is not a complete solution.
“There’s no way you can cheat when it’s about sleep,” June Lo, assistant professor at the Center for Sleep and Cognition at NUS and co-author of the study told The Washington Post.
The current evidence highlights the complexity of how sleep patterns affect mental state, underscoring the need for more research to understand how working adults can mitigate the effects of sleep loss.
Meanwhile, the authors emphasize the importance of consistent and sufficient sleep according to age-specific recommendations, for optimal brain performance.
“I know we struggle to do that. Just try to stick to that as much as you can,” Lo said.
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Source: National University of Singapore ; Image: Freepik
The article can be found at Neurobehavioral functions during recurrent periods of sleep restriction: effects of intra-individual variability in sleep duration.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.
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