system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does oversleeping make us feel tired?
gpt
It often depends on where in your sleep cycle you wake up. Waking up during the deeper periods of the sleep cycle can leave you feeling significantly more groggy. Oversleeping could lead you into that deeper sleep where you are then awoken and you feel more tired. However, waking up during a lighter period can allow you to become more alert more quickly and even if you didn't get a lot of sleep, you can still feel more energetic.