Electrophysiological Mechanisms of Sleep Homeostasis / 生物化学与生物物理进展

The brain’s neural circuits consist of a large number of highly unstable networks. Despite the existence of many internal and external factors that continuously disturb the balance, our brains employ an array of homeostatic mechanisms that allow neurons or neural circuits to sense how active they are, and when they deviate from a target value, whereby a force must be generated to move neuronal activity back toward this target. Sleep is one of the well-known physiological states in the regulation of homeostasis. Sleep pressure increases during wakefulness and decreases during sleep. When sleep is lost (e.g., sleep deprivation), this loss is compensated by extending or strengthening subsequent sleep. These phenomena are known as sleep homeostasis. The dysregulation of sleep homeostasis accompanies brain-related diseases such as schizophrenia, bipolar disorder, major depressive disorder, and autism spectrum disorder. More importantly, it can significantly undermine the basis of traditional sleep hygiene practices for these diseases. Therefore, clarifying the mechanisms of sleep homeostasis is important for therapy, but it remains an unsolved mystery. In addition to pharmacological treatment, non-invasive brain stimulation has become one of the most promising tools for clinical treatment in recent years due to its low cost, portability and low incidence of side effects. In order to promote relevant technologies, this review will focus on the electrophysiological mechanisms of sleep homeostasis. We first discuss the electrophysiological marker of sleep homeostasis, slow-wave activity, then move to the neuronal firing rates, finally discuss more aspects of sleep homeostasis, including differences in brain area, sleep stages, learning and individual differences.

The regulatory mechanism of physiological sleep-wake / 中国药理学通报

This paper explains the mechanism of the mutual switching between physiological sleep and wakefulness from the aspects of the sleep circadian system and the sleep homeostasis system. In the circadian rhythm system, with the suprachiasmatic nucleus as the core, the anatomical connections between the suprachiasmatic nucleusand various systems that affect sleep are summarized, starting from the suprachiasmatic nucleus, passing through the four pathways of the melatonin system, namely, subventricular area of the hypothalamus, the ventrolateral nucleus of the preoptic area, orexin neurons, and melatonin, then the related mechanisms of their regulation of sleep and wakefulness are expounded. In the sleep homeostasis system, with adenosine and prostaglandin D2 as targets, the role of hypnogen in sleep arousal mechanisms in regulation is also expounded.