system
Given the following post, respond as if you're commenting on Reddit:
human
Do peoole in comas have cycles like sleep/wake for brain activity or is a general muted brain activity the whole time?
gpt
In general, a coma is a state of unconsciousness you can't be awakened from. The brain doesn't go through normal sleep cycles and you can't move in response to pain. Comas are caused by brain damage from head injuries or illness.

However some coma patients (up to 15% of patients) can show normal looking brain activity.