The alerting effect of the wake maintenance zone during 40 hours of sleep deprivation

Jan De Zeeuw,Dieter Kunz,Mirjam Münch,Amely Wahnschaffe,Alexandra Papakonstantinou,Sophia Wisniewski,Frederik Bes,Mandy Zaleska

doi:10.1038/s41598-018-29380-z

Abstract

Under entrained conditions, the accumulation of homeostatic sleep pressure in the evening is opposed by a strong circadian arousal signal prior to the dim light melatonin onset, called the Wake Maintenance Zone (WMZ). This study aimed at investigating the impact of the WMZ on different cognitive performance tests, as well as on subjective and objective sleepiness. Twelve young male participants completed a constant routine protocol with 40 h of extended wakefulness that included two WMZs. Cognitive tests and saliva samples were assessed hourly, while the electroencephalogram (EEG) was recorded continuously. Participants improved in cognitive response inhibition during WMZ1 (13.5 h awake) and sustained attention during WMZ2 (37.5 h awake), but not in higher executive function tests. There were significant EEG power density reductions in the delta/theta frequency range during WMZ1 and in delta/theta, alpha, and sigma/beta ranges during WMZ2, with a greater change in the sigma/beta range during WMZ2 compared to WMZ1. EEG power reductions coincided during WMZ1 with stable subjective sleepiness and sustained attention. During WMZ2, EEG power reductions were more pronounced and coincided with improved sustained attention. Our results suggest the circadian arousal signal in the evening differently modulates cognitive functions and EEG power depending on the duration of prior wakefulness.

Highlights

Mammalian sleep-wake regulation undergoes modulation by two main processes
Better working memory performance during the wake maintenance zone’ (WMZ) has been linked to sleep-dependent higher hypothalamic activation as assessed in the Blood Oxygenation Level Dependent (BOLD) response of the MRI after a normal duration of prior wakefulness, but not after very low or very high sleep pressure conditions[25]
EEG delta/theta and sigma/beta activity increased over time and demonstrated a circadian influence by revealing a significant power reduction during the WMZs when compared to the preceding hour

Summary

Introduction

Mammalian sleep-wake regulation undergoes modulation by two main processes. A homeostatic process (Process S) accounts for the build-up of sleep pressure, i.e. it increases with time awake. Better working memory performance during the WMZ has been linked to sleep-dependent higher hypothalamic activation as assessed in the Blood Oxygenation Level Dependent (BOLD) response of the MRI after a normal duration of prior wakefulness, but not after very low or very high sleep pressure conditions[25]. These studies suggest a differential impact on cognitive performance during the WMZ, depending on the duration of prior wakefulness. We expected differences in subjective and objective sleepiness between both WMZs, which depend on the prior duration of wakefulness

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