system
Given the following post, respond as if you're commenting on Reddit:
human
How do you actually wake up?

My question is when you are asleep, when your wake up response is triggered, are some chemicals released to force you body to wake or is something else going on? 

To go along with it, how would waking up from a distraction, such as light or sound be treated by your body differently than if you went to sleep in a quiet, dark room and just slept until your body woke up naturally?
gpt
Propensity to sleep is regulated by both circadian rhythms and homeostatic sleep pressure, which interact in what we call the "two-process model." Waking up is not due to just 'circadian cycles.'

The actual wake response consists of multiple brain regions, particularly brainstem wake-promoting regions, which release a variety of neurotransmitters (eg. acetylcholine, norepinephrine, glutamate, etc.). These 'wake-on' regions can target the cortex through intermediary structures like the thalamus or basal forebrain. 

Waking up from an external stimuli is possible because there is still rudimentary sensory processing during sleep, but the actual 'waking up' part is likely mediated by at least some of the same circuitry that causes 'natural' waking up.