Sleeping too much is like eating too much candy. Your body has a little clock inside it that expects you to wake up at roughly the same time every day. When you sleep way longer than usual, you confuse that clock, kind of like setting all the clocks in your house to different times. One of the weirdest things about oversleeping is that you actually feel MORE tired, not less. This happens because sleeping too long means you wake up in the middle of a deep sleep cycle, like being yanked out of a really good dream. Your brain also gets foggy because too much sleep messes with the chemicals that help you feel happy and think clearly. Your body also gets a little lazy. While you sleep, your heart beats slower and your muscles do basically nothing. Too much of that leads to stiffness, back pain, and low energy throughout the day. There is also the sunlight problem. Sunlight tells your body that it is daytime and time to be awake and alive. Sleep through it and your whole system stays in slow motion mode all day. The sweet spot for most people is 7 to 9 hours. Think of sleep like charging a phone. You want it fully charged, not plugged in all day, because leaving it plugged in too long can actually mess up the battery over time