Why do I get nightmares when I fall asleep while lying on my left side?

the left side is the sinister side!

@La_chica_gomela Haha! I’d already thought of that! (Hence the tags.)

I used to get nightmares when I slept on my back.
Now I just get weird dreams.
My theory is that there something about sleeping on my back that would wake me up during a dream, and therefore I’d remember it. Otherwise I don’t tend to remember my dreams.

So my answer is: I don’t have a clue, but it’s a great question.

I always thought it had something to do with the side of the brain that was getting more blood because of gravity or was being put under more pressure. Something on that side may fire different synapses.

Dunno.

Nimis, you’re adorably weird.

Thanks?

You’re welcome! :)

Hmm, I wish I had time to look up what happens on the left side of the brain. Then I could type out some really long and smart looking answer that says it’s because the blood pools on that side when you lay down, but I’m swamped at work. Pretend I came up with a brilliant answer just his once, ok??

Great question by the way!

wiki says some pretty good stuff, and this site has a map that helps understand left brain function pretty well.

But the left side of the brain is the logical one, the one we use for calculations and so on. So, unless you fall asleep worrying about your finances and end up with a nightmare, that’s not it. Would make more sense if it was the right side.

One possibility (and I know my father is in that category) is that because your heart is on the left, you’re perhaps squeezing it. This would be even worse if you have some extra weight, excess fat, bad circulation. Do you smoke? All of these could be factors.

Of course the solution would simply be to sleep on the other side.

Personally I keep twisting and turning every 2.3 seconds, which is why no woman would ever want to share the bed with me. My girlfriend doesn’t even want to spend the same city sector.

@Jack79 Yeah. I was trying to figure that one out myself.
My nightmares are pretty trippy. Well, so are my dreams.
If I had to choose, I’d have guessed right hemisphere.

The other thing that makes sense is placement of the heart.
Though that by itself shouldn’t matter, right? It’s the same for everyone.
Therefore there must be another underlying issue.
Though I don’t think it’s any of the ones you mentioned.

I’m well within the normal BMI.
And while I do smoke, it’s really not that often.
I have bad circulation, but I think most women do.
But they don’t seem to have this weird problem.

If my heart is indeed emo kids are going to swoon getting crushed
when I’m lying on my left side, why does it not cause a problem
when I roll over to my left side in the middle of my sleep?
It’s only an issue as I fall asleep.

My SO rolls me over to my right side before I fall asleep.
Sufficiently avoids the issue, but it’s still rather peculiar.

Why do you think most women have bad circulation, Nimis?

All my female friends always have cold hands and feet. Assuming poor circulation to extremities?
Plus I think someone mentioned that most women are slightly anemic. Asmonet?

real mystery.

So let me get this straight: you only have this problem if you fall asleep while on that side, but not if you were lying on that side either before or during?

The only other explanation would be that you have subconsciously connected that particular position with some bad experience.

For example everytime I shave, I get to that particular stroke on my left cheek, and everytime I think of this situation some 10 years ago when I was telling someone something while shaving. Not even important as a fact, but it is connected to the particular movement. So maybe the position evokes some unpleasant memory that causes the nightmare?

Is it a recurring nightmare?

In order:
Indeed.
Yes. Only as I fall asleep.
No. None that I can think of.
Interesting.
Sometimes. But not recently.

I wouldn’t say that most women have cold hands and feet or that they’re anemic, but I don’t know what anemia would be related to circulation except that they both have to do with blood.

I swear, there’s been a study for freaking everything

Sleep and Hypnosis published a study of 63 subjects that looked for a correlation between sleep position and dream quality. It found that 40.9% of left-side sleepers suffered nightmares, compared to 14.6% of right-side sleepers. Right-side sleepers reported slightly more positive emotions in dreaming than the left-siders, and experienced better overall sleep quality.

The researchers don’t offer any speculation as to the cause, I’m afraid, Nimis. They do plan to follow this up with a larger study using polysomnography, so maybe later.

I am, by the way, very impressed that you made this connection!

@Harp Good stuff, Harp.
Geez. There has been a study for everything, eh?

@La_chica_gomela Ermm…can I switch that to many then?

@nimis, okay. ;-)
also, don’t you love harp? whenever i finish reading harp’s answers, i’m overwhelmed with wow. i had no idea about the right-left thing.

@La_chica_gomela Yes, I am the mostestest sad that I have out-lurved him.

ok, so after reading this question last night I went to sleep on my left side. And had a nightmare. So there’s no coincidence in the statistics I think, there is some connection there. My money would be on some sort of heart relationship, not brain. Because contrary to common belief, human bodies are not symmetrical. There is a heart on the left side and not on the right one. So my guess is that we’re somehow giving it a hard time by sleeping on it.

Oh shit! Really?
That is fucking crazy.

Maybe it’s not weird that I get nightmares.
But that I noticed the correlation. Ha.

Hmmm…maybe I should ask the rest of the collective? Now I’m kind of curious.

Mind you, yesterday was such a bad day for me that I would probably have had a nightmare anyway. But Harp’s statistic seems interesting. I wouldn’t have paid attention if it was 5% to 7%, but 14 to 40, that’s almost triple, it can’t just be a coincidence.

Awww…hope tomorrow is better.

no, it will only get worse from here, but it’s something I have to go through. With fingers crossed that there’s an exit on the other side

Beeline for the exit, my friend. Beeline for the exit.
In the meantime, sleep on your right side & good night!

Actually I had an epiphany last night when I was about to fall asleep! So I was thinking about the whole Latin/left/sinistra/sinister thing, and it occurred to me that since

(A) Romans generally saw dreams as important or often prophetic, AND
(B) sinister literally means “reclining to the left”

Maybe the phenomenon Harp cited is where the whole “left = sinister” thing came from. I’m sure they didn’t do clinical studies, but perhaps they began to notice that the one was more likely to have bad dreams when reclining/sleeping on the left side, and thus the association was born.

I thought both sinistre and sinister simply meant left or unlucky.
Hadn’t yet heard of it meaning reclining to the left.
That’s interesting food for thought, chica!

Well, you know I could be wrong about the reclining. I just looked at dictionary.com, and it didn’t mention it. I wish I could access the OED right now to find out for sure one way or the other.

@Nimis: Not necessarily relevant, but some people do have organs in the wrong place. When it’s just the heart it’s called Dextrocardia. :)

Your heart comment reminded me of it, interesting stuff even if it doesn’t apply to you specifically.

Whoa. That’s trippy.

I know right?! God damn, I love Discovery Health.

hi gang! I’m Adam. I stumbled on this site while looking up sleep position and nightmares because I TOO have nightmares almost every time I sleep on my left side. Last night was no exception. This time, though, I forced myself awake and wrote down a few pages worth of the dream; This of course, after I had tried to wake myself up in the dream probably 5 or 6 times only to wake up (lucidly) in another dream. Maybe I should use this for another question, but do any of you have lucid dreams where you almost can’t wake up? (maybe I was just really in need of the REM sleep)

Hey everybody,

I actually looked up on google “Why do I dream when I fall asleep on a certain side?”, which happens to be my left side. Although I sleep on my back, I usually have my head lying to the right, but recently I found it more comfortable to lie it to the left, and since I’ve started doing that I’ve had a dream almost every night. I don’t think it’s connected to my heart because it’s the same as I’ve always slept. They’re not always nightmares, but some are really weird, although last night I remembered 3 of my dreams. 2 “nightmares” (although not that frightening, unless you count getting bitten by purple caterpillars or living with a family of teenage robots scary(although my greatest fear is humanoid robots)) and 1 just plain weird one.

I think that it could be connected to an event in my past, because I used to always sleep on my left side until my sister asked me why I wasn’t afraid that monsters would sneak up on me (my bed is against the wall on the left side) and since then I’ve been afriad to sleep on that side. Silly I know.

All of your ideas were very interesting to read and I hope we soon find the answer!

I hope this discussion is still
Up? I sleep better on my left side but I almost instant get nightmares.

@DreamHater It would not appear to be active any longer, but if you wish to get additional input, feel free to ask the question again as it has been quite some time since the question was asked/got a response.

@Fly Thanks. It’s been two years ago since the last post I see. I’m on my phone is it still possible to answer a question. (sorry I’m new)

@DreamHater You can do anything from the mobile site that you can do on the full site. Just use the link that says “ask a question” on the home page of the mobile site.

I know this Q is long past but… I recently (2018) had a bout of diverticulitis that eventually developed into a perforated sigmoid colon.
When I moved on to my left side I had pains that caused all sorts of night mares. I had to force myself to sleep on my right side.