Abstract
PurposeTo reveal the physiological mechanism of the decline in cognitive function after sleep deprivation, a within-subject study was performed to assess sleep deprivation effects on phase synchronization, as revealed by wavelet phase coherence (WPCO) analysis of prefrontal tissue oxyhemoglobin signals.Materials and MethodsTwenty subjects (10 male and 10 female, 25.5 ± 3.5 years old) were recruited to participate in two tests: one without sleep deprivation (group A) and the other with 24 h of sleep deprivation (group B). Before the test, each subject underwent a subjective evaluation using visual analog scales. A cognitive task was performed by judging three random numbers. Continuous recordings of the near-infrared spectroscopy (NIRS) signals were obtained from both the left and right prefrontal lobes during rest, task, and post-task periods. The WPCO of cerebral Delta [HbO2] signals were analyzed for these three periods for both groups A and B.ResultsSix frequency intervals were defined: I: 0.6–2 Hz (cardiac activity), II: 0.145–0.6 Hz (respiratory activity), III: 0.052–0.145 Hz (myogenic activity), IV: 0.021–0.052 Hz (neurogenic activity), V: 0.0095–0.021 Hz (nitric oxide related endothelial activity) and VI: 0.005–0.0095 Hz (non-nitric oxide related endothelial activity). WPCO in intervals III (F = 5.955, p = 0.02) and V (F = 4.7, p = 0.037) was significantly lower in group B than in group A at rest. During the task period, WPCO in intervals III (F = 5.175, p = 0.029) and IV (F = 4.585, p = 0.039) was significantly lower in group B compared with group A. In the post-task recovery period, the WPCO in interval III (F = 6.125, p = 0.02) was significantly lower in group B compared with group A. Reaction time was significantly prolonged, and the accuracy rate and F1 score both declined after sleep deprivation.ConclusionsThe decline in WPCO after sleep deprivation indicates reduced phase synchronization between left and right prefrontal oxyhemoglobin oscillations, which may contribute to the diminished cognitive function.
Highlights
Sleep is a neural state, during which both memory consolidation and homeostatic preservations take place [1, 2]
The decline in wavelet phase coherence (WPCO) after sleep deprivation indicates reduced phase synchronization between left and right prefrontal oxyhemoglobin oscillations, which may contribute to the diminished cognitive function
Changes in cerebral activation are shown to occur as a function of sleep deprivation, and these changes are correlated with cognitive performance [10]
Summary
Sleep is a neural state, during which both memory consolidation and homeostatic preservations take place [1, 2]. Significant brain activity in different regions is occurring to form networks for optimal information processing in a waken state [3,4,5]. Sleep deprivation has various effects on human performance and neural functions, which are reflected in different description levels [6]. It could reduce a subject’s vigilance, raise the risk in decision making, and affect cognitive behavior, as well as a decrease sustained attention, cause an increased error rate and memory impairment [7]. The research into brain function mechanisms is very important when studying of the effects of sleep deprivation on cognitive function
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