Why does 12 hours of sleep make you feel so crappy?



I just don’t understand, some days, usually on weekends, I’ll try and wake up after a normal amount of sleep (like 7.5-8 hours) but I feel too exhausted to wake up.

Then I’ll end up sleeping like 12 hours and I feel like crap all day. Why is this?

In: Biology

You’re waking up during the deep sleep part of your sleep cycle, or REM sleep. Download sleep cycle and it’ll wake you up when you’re at a lighter point

You dehydrate when you sleep. 12 hours with no hydration is a long time. Regardless of how long you sleep, drinking some water when you wake up will help you wake up faster.

I’m guessing you slept too little during the previous week, and didn’t get enough catch up sleep even at 12 hours.

Am I right?

It seems like you might be having a bigger issues than just oversleeping on weekends. Generally to feel your best you should be going to bed and waking up at the same time every day (including weekends) and getting 8 hours of sleep. If you aren’t doing this that could be the reason you feel the need to oversleep in the first place. It could also be that you naturally feel groggy in the morning and actually just need to get up and start the day on 8 hours sleep even if you feel tired. If this is a persistent issue talk to your doctor, sleep is more important than many of us realize.

Sleep is unfortunately very poorly understood.

Most biological necessities, like food, water, and oxygen, have very easy to observe effects on the body. Food is broken down by the digestive system, an entire system of the body with a half dozen organs devoted to it, and turned into energy stores used by nearly every cell of the body. Water is the solvent of the solutions that fill our cells, the spaces between our cells, and the insides of multiple organs. Oxygen accepts electrons as the final step in the electron transport chain, the series of steps that produce most of the body’s ATP.

But sleep has subtle effects on nearly every system on the body, through layers and layers of indirect effects, and it’s not like we’ve got an organ or two devoted strictly to handling sleep, or not one that we know about anyway.

While I understand that this isn’t a very satisfying answer, and you’re likely to get plenty of answers without any scientific basis that at least feel more comforting, the most likely answer to your question is that we don’t know. There may be some obscure bit of research some academic sleep lab or another has published at some point trying to provide a reason for why too much sleep leaves you groggy, but ultimately your answer probably sits in the “things we don’t know” corner of science.

If I had to make some sort of educated guess though, I’d remind you that too much or too little food can make you feel bad, as can too much or too little water, certainly too little oxygen, and while you likely haven’t had a chance to experience it, too much as well. Most of our biological necessities, perhaps all of them, have a “happy medium” range where we are most healthy and most comfortable. There isn’t much reason to assume sleep is different. We already know sleep deprivation is at least mildly unpleasant for most of us, is it really that strange to think that too much sleep is any different?

If you were sleep-deprived enough to sleep for 12, you may have been sleep-deprived enough to need way more than 12 but the body can only rest for so long without needing to get food, water, etc.

You may have cause and effect reversed. You may be sleeping 12 hours, waking exhausted and feeling “crappy” all day because you are depressed. Disordered sleep is a symptom of clinical depression. Definitely something to speak to your doctor about.

Monkey have 8 banana monkey feel good but if monkey have 12 banana monkey overeat then monkey feel bad

There are three major reasons for that:

1.) Your sleep cycle: The average person goes through four to six sleep cycles per night. Each one of those cycles is approximately 90 minutes long. To put it simply, there is light sleep, deep sleep and REM sleep (this is when you dream) in every sleep cycle and the longer you sleep the longer gets the REM part of your sleep cycle. This is also the reason you dream a lot (and a lot of nonsense) when you sleep longer than usually. Now, waking up from REM sleep, doesn’t feel that good and you are often very confused, especially after longer periods of REM sleep.

2.) Your biological clock (also known as the “circadian rhythm”: You have to understand that *each and* *every* cell in your body is a seperate clock. They all add up to your “circadian rhythm” – which is essentially your body controlling all of your metabolic system through the release of hormones and the accumulation of waste material (All of it together says your brain when to feel awake or tired). Whenever there is a disturbance of your biological clock (e.g. sleeping longer or shorter than usually or flying overseas -> Jetlag) it causes a mess in your endocrine system (hormone system) and you feel tired and dizzy. This is also *very* simplified but you can read up on chronobiology if you want to understand more.

3.) Your personal lifestyle, age and genetics: How much sleep you really need is strongly influenced by your age (older people need less, children and teenagers need more) and your genetics (There are indeed *chronotypes* – such as owls and larks/morning persons and evening persons; this is not only a saying but scientifically proven.) Whenever you sleep less or more than you need to according to your age and genetics it leads to point 2.).

Finally, if your working night shifts and if you don’t have fixed sleep habits it leads to a messed up sleep cycle (point 1) and your biological clock stops working properly.

*I’m a German medical student and we were very lucky to hear a lot about sleep science, because one of our profs is very dedicated to the field. You can grab any book on chronobiology to read up more on that. By the way, the discovery of the biological clock was awarded with the nobel prize only in the year 2017:


Here some additional literature on the topic:



Sounds like you are not dealing with a problem in the amount of sleep you get, but rather the quality of your sleep.

Try a couple of things:
– force yourself to wakeup when your alarm goes off, despite feeling exhausted.
– drink a full glass of water when woken up.
– no screens 1 hour before you go to sleep. The blue light will mess with your melatonin levels en your sleep quality. Try reading a book instead.
– no caffeine in the evening, but ideally no caffeine after lunch. Caffeine has a half life of about 8 hours which means any caffeinated drinks in the afternoon will impact your sleep quality.

If would like to get more info on sleep, I’d suggest reading up on some research by Matthew Walker, or his book ‘why we sleep’. It definitely helped me better my sleep behaviour 🙂

For me this is usually because I feel like crap if I wake up any time after around 8am because it just makes me feel unproductive. If I get 12 hours sleep, the chances are it’s after 8am.

A couple of times in my life I’ve fallen asleep super early, had a 12 hour sleep and been awake for 7am and that feels awesome.