system
Given the following post, respond as if you're commenting on Reddit:
human
Without an alarm or other external source for waking us up, what prevents our brains from being asleep forever?
gpt
You have a really complicated internal clock called your circadian rythym that helps you know when to sleep and wake up. In short you have neurons that run in a loop, activating and deactivating themselves (a bit like a Redstone clock actually if you play minecraft), and similar proteins too that inhibit their own production so they come in waves. Essentially, using these complicated systems and synchronizing them frequently with light and other stimuli, your body can determine when to sleep, when to wake up, how to regulate temperature, and so on. This system would wake us up after about eight hours of sleep by stopping melatonin, and increasing seratonin, dopamine, acetylcholine, and norepinephrine production. Without the external cues though our body has a tendency to drift from 24 sleep cycles to slightly longer cycles (anywhere from 15 minutes to several hours longer, depending on the study.)