Reaction of the endogenous regulatory mechanisms to early weekday wakeups: a review of its popular explanations in light of model-based simulations

Weekday and weekend sleep times across the human lifespan: a model-based simulation

PURPOSE

The shifts in the opposite directions, toward later and earlier sleep timing, occur during the transition through adolescence and adulthood, respectively. Such a n-shape of age-associated change in sleep timing does not resemble the inverse relationship of sleep duration with ages. Age-associated variation in the parameters of the mechanisms of circadian and homeostatic regulation of sleep would underlie these different shapes of relationship of sleep times with ages. Here, we searched for a parsimonious explanation of these different shapes by simulating sleep times on weekdays and weekends with one of the variants of the two-process model of sleep regulation.

METHODS

Using mean age of a sample with reported sleep times on weekdays and weekends, the whole set of 1404 such samples was subdivided into 15 age subsets. Simulations of sleep times in these subsets were performed with and without the suggestion of age-associated variation in the circadian phase.

RESULTS

Simulations showed that the age-associated decay of slow-wave activity can parsimoniously explain not only the parallel decreases in weekend sleep duration and rate of the buildup of sleep pressure during the wake phase of the sleep-wake cycle, but also both the delay and advance of sleep timing during the transition through adolescence and adulthood, respectively.

CONCLUSION

The almost functional relationships were revealed between the age-related changes in sleep duration, rate of the buildup of sleep pressure, and slow-wave activity that is a good electrophysiological marker of cortical metabolic rate and synaptic density, strength and efficacy.

Can the Brain's Thermostatic Mechanism Generate Sleep-Wake and NREM-REM Sleep Cycles? A Nested Doll Model of Sleep-Regulating Processes

Evidence is gradually accumulating in support of the hypothesis that a process of thermostatic brain cooling and warming underlies sleep cycles, i.e., the alternations between non-rapid-eye-movement and rapid-eye-movement sleep throughout the sleep phase of the sleep-wake cycle. A mathematical thermostat model predicts an exponential shape of fluctuations in temperature above and below the desired temperature setpoint. If the thermostatic process underlies sleep cycles, can this model explain the mechanisms governing the sleep cyclicities in humans? The proposed nested doll model incorporates Process s generating sleep cycles into Process S generating sleep-wake cycles of the two-process model of sleep-wake regulation. Process s produces ultradian fluctuations around the setpoint, while Process S turns this setpoint up and down in accord with the durations of the preceding wake phase and the following sleep phase of the sleep-wake cycle, respectively. Predictions of the model were obtained in an in silico study and confirmed by simulations of oscillations of spectral electroencephalographic indexes of sleep regulation obtained from night sleep and multiple napping attempts. Only simple-inverse exponential and exponential-functions from the thermostatic model were used for predictions and simulations of rather complex and varying shapes of sleep cycles during an all-night sleep episode. To further test the proposed model, experiments on mammal species with monophasic sleep are required. If supported, this model can provide a valuable framework for understanding the involvement of sleep-wake regulatory processes in the mechanism of thermostatic brain cooling/warming.

Non-Pharmacological Intervention for Personalizing Sleep Quality through Gentle Rocking Motion

INTRODUCTION

Achieving restorative sleep is crucial for overall well-being, yet sleep difficulties affect a substantial portion of the adult population. Sleep disturbances are associated with diminished quality of life, physical complaints, cognitive impairment, and emotional regulation challenges.

OBJECTIVE

This study explores the influence of an innovative experimental bed designed to generate rocking motions on sleep parameters.

METHODS

A prospective observational study enrolled 60 adult participants, assessing their sleep on a regular stationary bed and the Inoveris bed, providing gentle rocking movements. Polysomnography was conducted, recording electroencephalography, electrooculogram, electromyogram, respiratory effort, and other parameters.

RESULTS

The rocking bed significantly increased total sleep time (TST) and reduced N1 sleep stage duration (p < 0.001). Participants also experienced a quicker transition to the N2 sleep stage (p = 0.01), indicative of a faster shift from wakefulness to deeper sleep. Additionally, rocking led to a higher percentage of N1 sleep stages (p = 0.01) and a significant increase in N3 sleep stage duration (p = 0.004). While some results lacked statistical significance, notable trends in the rocking bed group have clinical relevance, consistently improving sleep parameters, including increased TST. The rocking bed also showed a trend towards higher sleep efficiency (SE) and sleep duration percentage, hinting at a potential overall enhancement in sleep quality.

CONCLUSION

This study contributes valuable insights into the potential benefits of rocking motions on sleep architecture. Despite variations in outcomes across studies, our results underscore the potential of rocking beds as a non-pharmacological intervention for enhancing sleep quality. Notable improvements in total sleep time (TST), N1 sleep stage reduction, and accelerated transitions to deeper sleep stages highlight the clinical relevance of rocking interventions. Further research, collaboration, and addressing the identified limitations will advance our understanding of the therapeutic applications of rocking motions in sleep science.