system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does sleeping for a long time make you feel tired and groggy?
gpt
Your body has a natural cycle referred to as circadian rhythm. If you do anything to throw it off, you can feel out of it. This includes sleeping longer than normal, and stuff like traveling time zones. When your body isn't a synched up to the activities you want to be doing, you won't feel at peak performance.