system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can you know when you've had enough sleep? If you can fall back asleep, are you not done?
gpt
*Enough* sleep is different for everyone. The common number is 8 hours of sleep a night - however this is based on statistical data. Other studies show that many people can function on less sleep with no side effects. You can know when you've had enough sleep when you do not have general sleep deprivation symptioms such as lethargy, depression, decreases in short term memory, concentration, etc. ( however other factors such as caffeine, alcohol, drug use, and medication can affect this )