Limited Association Between 1-Night Sleep Restriction and Cognitive Performance

Even with only 1 night of restricted sleep, individuals exhibit increased feelings of sleepiness and decreased attention capacity, according to a recent study published in Sleep Medicine Reviews.¹

Portrait of Sleep-deprived Working Individual | image credit: Drobot Dean - stock.adobe.com

Sleep restriction (SR) occurs when someone’s sleep falls short of general recommendations or their personal preferences. As SR can be common, the present authors mention how growing research efforts have dedicated resources to investigating the impact of SR on cognitive functions.

A 2023 biological review conducted by Mohammad A. Kahn, MD, MRCP, and Hamdan Al-Jahdali, MD, MRCP, assessed the link between cognitive performance and sleep deprivation (SD). Throughout their investigation, the adverse consequences of SD were apparent.

“Neurological pathways slow down, causing a reduced reaction time and mental state,” Kahn and Al-Jahdali concluded. “Systems in the body enters a state of life-support as a means of coping until the brain can be re-stimulated. Fluctuations in the thalamic activity, synaptic renormalization, glymphatic system roles, DMN activity, amygdala activity and hippocampal activity can cause unequal stimulation in the brain, which results in irregular activities in the brain to manage SD. As a result, an impairment in attentiveness, working memory, consolidation of memories, alertness, judgement, decision-making, and many other diminished cognitive performances will follow.”²

While Kahn and Al-Jahdali cite prior studies that indicate these effects can take place after a single restless night, the authors of the present study note how literature in this area is somewhat limited and offers conflicting conclusions.¹ Some studies indicate significant cognitive impacts after 1 night of SR; however, these conclusions vary and sometimes rely on subjective self-reporting. As the causal relationship between 1 night of SR and cognitive functioning remains systematically unclear, Larissa N Wüst, lead investigator, et al conducted an analysis to summarize available findings on basic cognitive performance (attention, choice making, working memory, inhibitory control, and cognitive throughput) and subjective sleepiness following 1-night SR.

In February 2023, the researchers used the search terms “sleep restriction” or “partial sleep deprivation” with “cognition”—but not “therapy”—to gather information from the PubMed, Web of Science, and Scopus databases. Eligible studies included a control condition, cognitive test results, healthy adults, and a SR difference of at least 2 hours of sleep duration.

A total of 44 studies that included 1087 participants were included. SR groups had an average sleep duration of just above 4 hours and controls had an average duration of just over 8 hours. Surveying these studies, a risk bias analysis on sustained attention reaction time (RT) showed a significant publication bias towards higher RTs following SR (P = .01). Additionally, the authors observed significant increases in subjective sleepiness compared to controls following 1-night SR (P < .0001); however, this discrepancy was not significantly linked to sleep duration for those in the SR group.

With an average RT of 29.4 milliseconds in sustained attention tasks, the meta-analysis revealed that 1-night SR contributed to significant increases in RT and lapses of attention (2.7 lapses; P < .001). The difference in RT for choice-making tasks between SR and control groups did not reach statistical significance. Furthermore, sleep duration and RT throughout either of these tasks was not associated.

SR and control conditions also did not demonstrate significant differences in cognitive tasks (speed, RT), nor cognitive performance (assessed by correct or answered errors in the digit symbol substitution task, visual search task, numbers cancellation, selective attention tasks, and others).

In a similar trend, work memory and inhibitory control was not significantly impacted by 1-night SR (summarized by findings of 5 and 7 studies, respectfully).

The authors pointed to the lack of statistical power of their meta-analysis and its demonstrated bias towards increased RT. Due to the limitations of their approach, they emphasized the need for more research dedicated to the influence of 1-night SR on cognitive function.

"These findings should raise awareness especially considering safety concerns, regarding everyday activities such as driving on one hand and occupational safety on the other," they concluded. "Awareness of negative consequences of a single night of SR might be raised through public health as well as occupation specific campaigns."

References

1. Wüst LN, Capdevila NC, Lane LT, Reichert CF, Lasauskaite R. Impact of one night sleep restriction on sleepiness and cognitive function: A systematic review and meta-analysis. Sleep Med Rev. Published online April 26, 2024. doi:10.1016/j.smrv.2024.101940

2. Khan MA, Al-Jahdali H. The consequences of sleep deprivation on cognitive performance. Neurosciences (Riyadh). 2023;28(2):91-99. doi:10.17712/nsj.2023.2.20220108