Why does my heart race and my blood pound when I wake up from a nap?

June 16, 2008 10:25 AM

Why does my heart race and my blood pound when I wake up from a nap?

This doesn't happen when I wake up from a regular sleep session, but if I nap during the day, I almost always wake up with the really unpleasant sensation of my blood racing through my veins and my pulse elevated. I'm 24 and female, not overweight and not unhealthy.

posted by tatiana wishbone to Health & Fitness (15 answers total)

The same thing happens to me occasionally, and I've always attributed it to waking up with a start - either scared because I fell asleep without intending to, or surprised to find myself waking up during the middle of the day.
posted by brozek at 10:28 AM on June 16, 2008

Semi-seconding the above-- could a hypnic jerk be causing you to wake up?
posted by Bardolph at 10:32 AM on June 16, 2008

Response by poster: I don't think it's hypnic jerk because I have those at night and am occasionally woken up by them, but it's a much different sensation. Hypnic jerks are just little twitches, right? Whereas this is a very specific feeling that persists when I'm already awake.
posted by tatiana wishbone at 10:35 AM on June 16, 2008

I'm a terrible napper. The times I do manage to drift off for a nap, this will usually happen to me exactly as you describe. I usually get a general sense of panic with it as well, seemingly from nowhere.
posted by jeff-o-matic at 10:35 AM on June 16, 2008

A little panic. I used to get that too ... mostly when I knew I could only nap for a finite period and was worried about waking up in time ... and when I lived with the boring man I would get them too...Sort of a panic that said, "Oh no. This really is your life. It wasn't a dream."

It helped me to have at least half an hour to nap and to set my alarm to something semi-soothing if possible (harder when you're using your cell phone as an alarm clock.)
posted by notjustfoxybrown at 10:47 AM on June 16, 2008

I know you say you're not unhealthy, but do you snore, or is there any chance you have sleep apnea? Finally, do you nap in a position different from normal sleeping? I suffer from sleep apnea and before I started using a CPAP machine, I'd wake myself up gasping for air, heart pounding, after not having breathed for a few seconds. If I try to nap without the CPAP, I'll wake myself up from snoring.
posted by kimota at 11:55 AM on June 16, 2008

kimota is right, apnea will do that to you.
posted by RussHy at 12:05 PM on June 16, 2008

Circadian rhythms affect various body systems, including temperature, blood pressure and pulse rate. When you sleep at night you're cooler, have lower blood pressure and a slower pulse rate. This isn't true when you sleep during the day, so you'll feel different when you wake up. Various hormones, such as cortisol, also follow the circadian rhythm, which could account for anxiety and panic upon waking from naps.
posted by xchmp at 12:08 PM on June 16, 2008

Going in a bit of a different direction... The same thing happens to me, but it can happen even if I don't sleep. Even if I just lay down for awhile during the day (it doesn't happen in the morning after sleeping all night) and then stand up, my heart goes a bit crazy. Is it happening to you when you wake up, or when you sit or stand up?
I read recently that for some people, going from a lying down for a bit of time, to a standing position can cause the pulse to race. I didn't ever read a satisfactory reason why this might be though.
posted by Ziggurat at 12:58 PM on June 16, 2008

Response by poster: Kimota & RussHY - I do actually snore a bit (maybe more than a bit?) and I also seem to require a lot more sleep than other people - I can sleep for 13-14 hours easily if undisturbed and I feel best if I get around 9-10 hours. What's puzzling about it is that I don't feel this way when I wake up in the morning.

Ziggurat - I sometimes get a rush of blood to the head when I stand up, which I think it what you mean, but this is a different feeling that just happens when I wake up.

xchmp - Interesting about the circadian rhythm, I hadn't thought about that before.
posted by tatiana wishbone at 1:14 PM on June 16, 2008

This happens to me every time I nap as well. I never feel anxious or that I was dreaming intensely or anything of that sort, just heart racing blood pressure high. It usually evens out after about 10 minutes or so.

I do also find that I have breathing issues, especially during a workout.

Thanks for posting this question and letting me leech some information!
posted by huxley at 1:45 PM on June 16, 2008

What are you eating before you sleep? For myself, I've noticed that bolting down anything really meaty, heavy, or salty (like a hamburger or fries) before a nap will leave me waking up completely dehydrated and devoid of energy. I get the same symptoms you describe, too, rapid heartbeat etc.

Additionally, how long are you napping? I (and probably everyone, but I don't have the science to back this up) swing in and out of periods of deep sleep, so a nap for 2 or 4 hours will refresh me while a 90 minute or 3 hour nap will leave me exhausted. Again, same symptoms.
posted by greenland at 2:13 PM on June 16, 2008

This also usually happens to me when napping, even when severely sleep-deprived, but never when waking up between 5 am and 10 am. I think it's just a rhythm thing as others have suggested -- not concerned about it being a symptom of a health problem for myself.
posted by ecsh at 2:50 PM on June 16, 2008

Do you nap in a chair rather than lying down? Postural orthostatic tachycardia syndrome (as featured in yesterday's NY Times Magazine) prevents the blood vessels in your legs from constricting normally when sitting, causing the heart to race and pound.
posted by nicwolff at 3:21 PM on June 16, 2008 [1 favorite]

I have the same thing. I always figured it was because my body had prepared itself for a good bit of sleep but, this being a nap, I woke after x minutes (resulting in a nasty body shock). Whereas, if you sleep a whole night and then wake up, even if it is too early for you and in the middle of a sleep cycle, at least your body had had the 6/7/8 hours of sleep and can handle waking up a bit better.

Of course this may be completely stupid, so I'm very interested in the real answer. Because right now I resist having naps just because I hate the waking up part.

(Also, how does one take a 20 minute nap? What if it takes 10 minutes to fall asleep?)
posted by Skyanth at 5:57 AM on June 17, 2008