Sleep debt can be understood as the cumulative effect of not getting enough sleep, leading not only physical, but mental fatigue regardless of cause. It most often occurs when insufficient hours of sleep are obtained to meet our individual sleep needs.
In this contemporary world, is common to think that if we sleep, we are losing productivity. However, on the contrary, if we do not sleep properly and if we have sleep debt our mental fogginess, will affect negatively our daytime function.
People may think that we can just “catch up on sleep on the weekend” but it doesn’t work in that way. Several investigations have demonstrated that sleep deficiency have a negative impact in our cognitive functioning during daytime and it also has physical effects in our cardiovascular, respiratory and neurological areas.
A recent study of Ochab and colleagues, had observed the changes in human functioning during induced sleep deficiency and they measured the effects of 7 days sleep recovery following 10 days of sleep restriction on performance, spontaneous locomotor activity, and EEG parameters in healthy adults. The study included 21 consecutive days divided into periods of 4 days of regular life (a baseline), 10 days of chronic partial sleep restriction (30% reduction relative to individual sleep need) and 7 days of recovery.
Participants completed the study in their normal day-to-day environments and wore wrist sensors (actigraphy) to monitor daily patterns of sleep and activity. They also underwent daily electroencephalography (EEG) to monitor brain activity, and they answered daily questions (Stroop tasks) to measure reaction times and accuracy. The subjects were asked to decide whether the name of the color matches with the ink in which it is written (congruent conditions) or not (incongruent conditions). So, the more automated task (reading the word) interfered with the less automated task (naming the ink color) resulting the difficulty in inhibiting more automated process known as the Stroop effect.
After 7 days of recovery, the participants had not yet returned to pre-sleep deprivation performance on most measures of functioning. The researchers observed unanimous deterioration in all the measures during sleep restriction. These included several EEG measures of brain activity, rest-versus-activity patterns captured by wrist sensors, and accuracy on Stroop tasks. Only their reaction times had recovered to baseline levels.
References
- Ochab JK, Szwed J, Oleś K, Bereś A, Chialvo DR, Domagalik A, et al. (2021) Observing changes in human functioning during induced sleep deficiency and recovery periods. PLoS ONE 16(9): e0255771. https://doi.org/10.1371/journal.pone.0255771
- “Deficits may remain after 7-day recovery from 10 days of insufficient sleep: In small study, reaction speed recovered, but other sleep loss deficits persisted one week later.” ScienceDaily. ScienceDaily, 1 September 2021. www.sciencedaily.com/releases/2021/09/210901142729.htm
