About this Research Topic
As brain and body structures and societies have become more complex, sleep has also evolved and diversified. As a result, the daily duration and frequency of sleep varies among animal species, but its physiological significance is still unknown. For example, among the same mammals, the average daily sleep time is 2 hours for giraffes, 20 hours for koalas, and 8 hours for humans. In the process of evolution from reptiles to birds, many methods were used to change the use and combination of existing genes, rather than acquiring new ones. The fact that the diversity of existing genes gave birth to various organisms suggests that diversity in sleep may also have been created through the use of existing regulatory systems. A sleep cycle in which non-rapid eye movement (NREM) and REM sleep are repeated at regular intervals exists in birds and mammals, but has not yet been confirmed in amphibians, the common ancestor of mammals and reptiles. In reptiles, a primitive REM-like state has also been shown to exist, which is an important report for exploring sleep evolution. In humans, NREM sleep and REM sleep are repeated in a 90-minute cycle, and it has been shown that brain metabolic rate decreases and brain temperature drops during NREM sleep, while neural activity is as active during REM sleep as during wakefulness. In other words, it is expected that the initial function of the sleep cycle can be explored by examining in detail the sleep state of reptiles, in which NREM sleep and REM sleep are thought to have begun to establish different functions.
This Research Topic aims to explore three questions. One is to elucidate which the neuronal population and neural circuits mediate sleep cycle. Second is to elucidate how and when neurons are formed, where they are located, and how they differentiate into cells with specific functions related to sleep. Third is to elucidate how the autonomic nervous system and endocrine system maintain homeostasis in the body, such as body temperature, blood pressure, and blood glucose levels, and regulate biological rhythms.
Therefore, we welcome papers on basic neuroscience, autonomic functional, translational, and clinical studies in this research topic, such as:
• Neuronal functions and circuits of sleep.
• Molecular mechanisms of sleep.
• Neuroembryology and sleep.
• Autonomic function mechanisms of sleep.
Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.