Now i may not be as smart as Cecil, but I do remember reading that the reason you are groggy after oversleeping is because of the hightened levels of melatonin in the system. Melatonin, as you may already know, is produced when you sleep and makes you sleepy, hence you stay asleep. So when you oversleep, there is hightened levels of melatonin, making you groggy when you wake up. Melatonin has normal circadiem rythmes that also cause people to fall asleep in the afternoon, where statistically more accidents occur because people fall asleep. I am not saying this is the only cause. I really enjoy your columns, and don’t take this personally, i could just be on a powertrip and totally full of it. thanks…
Welcome to the Straight Dope Message Boards, b3286, glad to have you with us.
When you start a thread, it’s helpful to others if you provide a link to the column you’re discussing, so we can all be on the same page (so to speak.) In this case: Why do you feel groggy after oversleeping?
I’m interested in the idea that melatonin has a daily cycle. Is that proven?
I once read something about Indian medicine which said the body had three eight-hour stages that corresponded with the day-- one was something like 2 pm to 10 pm, one was 10 pm to 6 am, and the other was 6 am to 2 pm.
If you had trouble sleeping, it was recommended that you go to bed before 10 pm, because the 2-10 period was a drowsy one. The 10-6 was a wide-awake one, and if you stayed up past 10 you’d have trouble getting to sleep. If you felt groggy after waking up you should try getting up before 6 in the morning. If you accidentally woke up before 6 and tried to get back to sleep, it would be really hard. The 6-2 period was moderately sleepy, so if you slept past 6 you might have trouble getting going.
It made sense-- I was particularly familiar with waking up at 4 or 5 and not being able to get back to sleep properly before my alarm went off at 7. I wondered when I read it if it was some kind of illusion that we fooled ourselves into thinking was really there, or if there was a physiological explanation for it.
i read about the melatonin levels in my high school psychology class. I took it last year, my sophomore year and it was a college course. I am fairly certain that studies have been done on this subject, hence it was published in the text book. I was really happy with the year of psychology that i took, and infact i insist that everybody at some time should look into this very interesting field of science.
Neat. I didn’t know they had psychology classes in highschool, either. 
Deffenetely neat-o. And they’re even letting High Schoolers use computers now! What a world we live in…
Errr… I was using a computer in high school in 1965…