How come it feels different to wake up after sleeping late?

You sleep in cycles – the first one is 3 hours, then each subsequent one is 2 hours. Waking up in the middle of a cycle is very disruptive. Thus, it’s more refreshing to wake up at 7 hours or 9 hours (or even 3 or 5 hours) than at 8 hours or 10 hours.

@papayalily
That doesn’t explain what we’re seeing. It’s eight hours either way, waking up should interrupt his fourth cycle in both cases. If your explanation is right, then he would feel groggy on normal days, too.

Most people have a Circadium Rhythm which is optimal for their body. This involves a lot of different processes like hormone release, core body temperature levels, response to light levels and a whole bunch of other stuff best explained by someone better versed in medicine than I.

The majority of the population (around 70%) fall into the typical 11–12pm sleep and 8 am waking cycle which you described in your first example.

When that is disrupted for any reason, your body gets thrown out of rhythm and is not operating at its normal peak efficiency. The amount of sleep is not the issue. It’s WHEN that sleep occurs in relation to your body and mind’s rhythm relative to other body functions.

I happen to be in that other unlucky 30% and don’t begin to approach optimum functioning until around noonish or so. It’s not that I can’t function in early am hours. It’s just that I don’t function as well. Grogginess, crabbiness, general unease etc.

It seems that your bod’s natural rhythm is in the first pattern you described. When you force it out of that pattern, you don’t feel right.

It wasn’t until I read a thorough explanation of the importance of Circadian rhythms that I finally understood why I thought I was an insomniac for so long. Once I stuck to my particular body’s preferred natural rhythm, (instead of society’s dictates) everything improved greatly.

Do a little reading up on the subject and try to follow your particular body rhythms and I think you’ll feel better for it in multiple ways.

The overall most easily accessible source of info on all of this for me personally was on the Stanford Univ. Site.

If you go to Stanford.edu and click on the first link that comes up when you put “circadian rhythm information” into their search it brings you to the page which is the best starting point. I found the part about the “clock gene” especially interesting for myself.

Because you were up more hours when you went to sleep late. If you had stayed up 30 hours straight, it would not surprise you that you might need 10 hours sleep rather than 8.

And, the requisite is not 8 hours. It depends on what you need. Some people are fine with 6, some need 9. Do you need an alarm to wake up after 8 hours? Then you might be slightly sleep deprived. Most people sleep in 1.5 hour cycles. When you catch a nap you might notice you sleep 1.5 or 3 hours. It varies by individual though. Most of my life I needed 9 hours sleep to feel well rested. That is changing a little now.

Sleep patterns are best kept regular and when the regularity is disrupted you will feel below par.

its the time that body follows thats why