sleepregulation

Sleep regulation refers to the complex biological processes that control when we fall asleep, when we wake up, and the structure of our sleep. It is primarily governed by two main systems: the circadian rhythm and the homeostatic sleep drive. The circadian rhythm is the body's internal biological clock, which operates on a roughly 24-hour cycle and is influenced by light exposure. It dictates periods of wakefulness and sleepiness throughout the day. The homeostatic sleep drive, also known as sleep pressure, builds up the longer we are awake. The longer we stay awake, the stronger this drive becomes, increasing our need for sleep.

These two systems interact to ensure we sleep when it's appropriate and get enough rest. For example, even if the homeostatic sleep drive is high, strong light signals can inhibit sleep onset due to the circadian rhythm promoting wakefulness. Conversely, as light fades in the evening, the circadian drive for sleep increases, coinciding with a high homeostatic sleep drive, making sleep more likely. Various hormones, neurotransmitters, and brain regions are involved in orchestrating these processes, including melatonin, adenosine, and the suprachiasmatic nucleus. Disruptions to these regulatory systems can lead to sleep disorders.