Sleep and wakefulness cycle from "summary" of Discovering the Brain by National Academy of Sciences,Institute of Medicine,Sandra Ackerman
The sleep and wakefulness cycle is a fundamental aspect of human biology that is governed by a complex interplay of internal and external factors. This cycle is regulated by a region of the brain known as the suprachiasmatic nucleus, which serves as the body's internal clock. The suprachiasmatic nucleus receives input from light-sensitive cells in the eyes, allowing it to synchronize the body's sleep-wake cycle with the natural day-night cycle. Throughout the night, the body progresses through several stages of sleep, each characterized by distinct patterns of brain activity. These stages include both rapid eye movement (REM) sleep and non-REM sleep, with REM sleep being associated with dreaming and heightened brain activity. Non-REM sleep is further divided into several stages, with deep sleep being the most restorative stage for the body. The transition between sleep and wakefulness is facilitated by the release of various neurotransmitters in the brain. During wakefulness, neurotransmitters such as acetylcholine and norepinephrine promote alertness and cognitive function. In contrast, during sleep, neurotransmitters such as serotonin and gamma-aminobutyric acid (GABA) help to induce relaxation and prepare the body for rest. Disruptions to the sleep and wakefulness cycle can have profound effects on both physical and mental health. Chronic sleep deprivation, for example, has been linked to a range of health problems, including obesity, diabetes, and cardiovascular disease. Additionally, disturbances in the sleep-wake cycle are a hallmark of sleep disorders such as insomnia and sleep apnea.- The sleep and wakefulness cycle is a critical aspect of human biology that plays a vital role in maintaining overall health and well-being. By understanding the mechanisms that regulate this cycle, researchers and healthcare providers can develop strategies to optimize sleep quality and promote better health outcomes for individuals.
