Eli5: why do we sometimes wake up in a really bad mood after a mid-afternoon nap?


This is something that happens to me from time to time since I was a kid.

I would take a nap after lunch, on a day like today. Then sometimes wake up feeling disoriented and depressed. Other times I’d feel fine.

What causes this specifically and why does it only happen sometimes?

In: 183

Are you waking up naturally from the nap or are you being woken up? For me it makes a difference – if I wake up naturally I generally just feel rested – but if I’m woken up, my mood seems to depend on where I was in the sleep cycle.

I was thinking that i am only one who experience this. I am careful to not sleep longer than 20 minutes. After power nap i am in good mood…ready to do anything in a minute. If i overslept for like and hour and fall into deep sleep and than wake up…i am generally in a very bad mood and angry for no reason and It took me significantly longer to get back on track.

I asked a doctor this once, a long time ago, and hopefully can mash together enough of their explanation to give you a vague start. When we sleep our brains are still very busy. Our chemistry changes too. There are different kinds of sleep, and different phases. Beyond that, things like dreams (which happen during a certain phase) can stimulate chemistry on their own (terrifying dream = cortisol or adrenaline in our bodies).

So, the answer is complex. Depends on what phases of sleep you had, what dreams you had, your specific cocktail of neurochemistry before, during, and after.

Think of your brain as a warehouse of memories.

The day crew stuffs new memory deliveries wherever they fit and pulls out any as necessary. When you sleep, the night crew helps clean and sort all the deliveries to their proper place.

When you nap, you swap to the night crew but can abruptly tell them to go home when you wake up. All the pallets of memories in transit could just be dumped in place, leaving you disoriented and sometimes feeling strong emotions of any of the pallets were carrying emotional memories.

I generally get these disorienting naps more often when I am stressed and the nap has to deal with moving all those emotional memories around.

Tangentially related, why do I wake up every morning in a really bad mood?