Gudowska-Nowak, E. | bioRxiv Science

bioRxiv2019

Observing changes in human functioning during induced sleep deficiency and recovery periods

The duration of sleep, wakefulness and dynamic changes in human performance are determined by neural and genetic mechanisms. Sleep deprivation and chronic restriction of sleep cause perturbations of circadian rhythmicity and degradation of waking alertness as reflected in attention, cognitive efficiency and memory. In this work we report on multiple neurobehavioral correlates of sleep loss in healthy adults in an unprecedented study comprising 21 consecutive days divided into periods of 4 days of regular life (a baseline), 10 days of chronic partial sleep restriction and 7 days of recovery. Throughout the whole experiment we continuously measured the spontaneous locomotor activity by means of actigraphy with 1-minute resolution in two acquisition modes (frequency and intensity of movement). Moreover, on daily basis the subjects were undergoing EEG measurements (64-electrodes with 500 Hz sampling frequency): resting state with eyes open and closed (RS; 8 minutes long each) followed by Stroop task (ST; 22 minutes). Altogether we analyzed actigraphy (distributions of rest and activity durations), behavioral measures (accuracy and reaction times from Stroop task) and EEG (amplitudes, latencies and scalp maps of event-related potentials from Stroop task and power spectra from resting states). The actigraphy measures clearly indicate rapid changes after sleep restriction onset, confirming our former investigations -- the novel insight is a slow and incomplete relaxation to the original locomotor behavior. The pattern of partial recovery appears also in accuracy (in ST) and power of delta rhythm (in RS). The impact of sleep loss is also evident in reaction times (in ST), yet followed by complete recovery, and finally in ERP amplitudes and latencies, which however did not return to the baseline at all. The results indicate that short periods (a few days) of recovery sleep subsequent to prolonged periods of sleep restriction are overall insufficient to recover fully.

neuroscience↗

bioRxiv2019

The effects of a 10-day partial sleep deprivation and the following recovery on cognitive functioning - a behavioural and EEG study.

Sleep deprivation is an important societal problem that affects millions of people around the world on a daily basis. Our study aimed to examine the impact of a partial sleep restriction and following recovery processes on cognitive information processing, as evaluated by the Stroop test. We tested 15 participants over a period of 21 consecutive days, divided into 3 sleep conditions: 4 days of typical daily routine (baseline, base), 10 days of partial sleep deprivation ( SD), and 7 days of recovery ( rec). Each day, participants took part in an EEG experiment in which they performed a Stroop test, lasting for about 30 minutes, that required them to make an appropriate response to congruent and incongruent stimuli. Additionally, every day they answered a number of questions regarding their subjective levels of sleepiness and mood. During the whole period of 21 days, participants spontaneous locomotor activity was measured with the use of actigraphy. We have found behavioural and neural changes associated with different sleep conditions, such that the 10-day period of partial sleep restriction was linked with poorer behavioural performance on the Stroop test and an attenuated P300 neural response, compared to the baseline, followed by the observation of slow and gradual return in the period of recovery. This study, the first longitudinal study of its kind, shows that partial sleep deprivation has detrimental, long-term consequences on both behavioural and neural levels. This adds to the growing body of literature on this important issue in modern societies.\n\nSummarySleep deprivation, a world-wide problem in the 21st century, is associated with a number of complications, such as motor vehicle accidents (Lyznicki et al., 1998; Goel et al., 2009), medical errors (Barger et al., 2006), poorer health (in Colten & Altevogt, 2006), as well as cognitive deficits including problems with working memory and attention (van Dongen et al., 2003; Lim & Dinges, 2008). While total sleep deprivation (that is, a complete lack of sleep in a 24-hour period) is usually reserved only to certain professions (such as medical doctors), partial sleep restriction (that is, reducing ones sleep time in a 24-hour period to fewer hours than typically required) is world-wide and affects a large proportion of the population across the globe. Taking this global impact into account, and thus increasing our understanding of the neurophysiological and cognitive processes that are linked with partial sleep deprivation, could largely inform the public discussion over what kind of impact, if any, restricting our sleep has on our daily functioning. This 21-day long EEG study investigated the effects of a prolonged (10-day) sleep restriction, and the recovery processes (over a 7-day period) that followed. Each day participants performed a Stroop test, known to measure attentional levels, and completed a number of sleep-related questionnaires. We have found that while behavioural responses are easier to recover, the neurophysiological responses are heavily affected after a period of sleep deprivation, with one week of recovery being insufficient to return to a pre-testing performance of an individual.

neuroscience↗