Why We Sleep Together

co-sleeping, sleeping together, sharing bed

Why do we share a bed with the one we love?

It is said that Rene Descartes developed the Cartesian coordinate system while lying in bed watching a fly crawl across the ceiling of his room. While no stroke of genius, I developed the thoughts below while lying tucked beneath the same set of bedclothes on the same mattress as my girlfriend—writhing in the excruciating pain of non-sleep.

My main thought: sleeping in the same bed with someone kind of sucks. I much prefer a space all to myself.

We want out of the system, but we don’t want to break from it. There is a first-mover disadvantage in a myriad of ways: hurt feelings, fears of rejection, disapproving comments from friends or family.

To continue with Descartes, the bed is a large rectangle. A couple lies together within that rectangle—usually under one set of bedclothes. This is a system. A system constrains the individual pieces of that system. There are the struggles for territory and comfort. The desire to achieve comfort while also not wanting your comfort to come at the expense of the comfort of the one next to you. This limited system requires these two moving parts to be in sync with each other—not only in terms of the sleep cycles but also their “comfort quirks”: their desired temperature, and other environmental factors like background noise or lighting.

As I write this, my girlfriend is asleep. She wasn’t asleep thirty minutes ago when I got up out of bed to come write this post. She was playing on her phone because she couldn’t get the nod. It could be that she would have fallen asleep had I stayed in the bed, but her insomnia follows a pattern. When I leave the bed in the middle of the night—as is my habit—she miraculously falls asleep. She sprawls out catty-corner across the bed—her arms splayed over into my evacuated hemisphere. Likewise, my best sleep is captured when she’s not in bed with me. When she heads to work in the morning on my days off, the few hours that I have the bed to myself make up the bulk of my quality sleep time.

I don’t think this is a very controversial topic, though I have received hostile looks and tsks when mentioning in the past that I’m not fond of sleeping next to another person whose body is putting off heat, whom I have to engage in an unconscious struggle for cover, and whose bodily movements jar me out of REM. It’s impossible to ignore that bed comfort is important in our society. We are concerned with the efficient use of time and sleep. We want eight hours of sleep—the more solid the better.

Mattress stores are about as common today as vitamin shops, organic markets, and gourmet coffeehouses. Consumers are dying for bed comfort, but they’ve yet to make a massive push towards decoupled sleep. Not only do we have the bed stores, but we have the Brookstone outlets that sell all sorts of sleep aid devices; we have the TV commercials advertising special comfort beds whose major selling points include isolated springs which prevent one person’s bed movement from disturbing the other. We want out of the system, but we don’t want to break from it. There is a first-mover disadvantage in a myriad of ways: hurt feelings, fears of rejection, disapproving comments from friends or family.

And then, of course, we have the covers. This is a widespread cultural meme—fighting for covers. This is the natural outcome of a systemic over- and under-lay. What we have is a turf battle on two fronts—one above and one below the couple lying in limbo. When presented this way, I have to ask, what is so great about sleeping in the same bed?

As we’d expect, research has been conducted on this topic, and it seems perfectly intuitive. Research from the University of Vienna found that when men slept with a partner they performed worse on cognitive tests than when they’d slept without a partner. They also displayed higher stress hormones. Women, on the other hand, did not display such drastic changes in mental ability and stress. They were able to reach deeper sleep when sleeping with a partner.

I also wonder if there are any latent frustrations stemming from the bed turf battle that later show up as relationship problems. As Dr. Neil Stanley at the University of Surrey said:

Historically, we have never been meant to sleep in the same bed as each other. It is a bizarre thing to do. Sleep is the most selfish thing you can do and it’s vital for good physical and mental health. Sharing the bed space with someone who is making noises and who you have to fight with for the duvet is not sensible. If you are happy sleeping together that’s great, but if not there is no shame in separate beds.

So what keeps us from admitting that coupled sleep is a drag? In a recent blog post, Dr. Robin Hanson believes that we trick ourselves:

This seems an obvious example of signaling aided by self-deception. It looks bad to your spouse to want to sleep apart. In the recent movie Hope Springs, sleeping apart is seen as a big sign of an unhealthy relation; most of us have internalized this association. So to be able to send the right sincere signal, we deceive ourselves into thinking we sleep better.

Instead of being about comfort or protection, co-sleeping is a signal on the part of each to remain committed to the same sham.

(h/t Andrew Sullivan)


Read more on Health, Psych & Addiction.

Image credit: jerine/Flickr

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  1. babe, i love you to the moon and back but, we really do need a bigger bed.

  2. Six months ago I read this post and was in a long distance relationship, living in different countries. All I wanted was to be able to sleep beside my man on a consistent basis.
    For the last three months we’ve been together – at last! I love him dearly and yet have had sub-optimum sleep ever since. The only time I sleep well is when I’ve been so frustrated I’ve flung myself elsewhere (first the couch and now the spare bed… often half way through the night, sometimes from the start).
    I have been physically wornout, mentally unsharp, and a cranky woman since sleeping with him. It has effected my moods, my motivation, and my weight as I eat more sugar and carbs when I’m tired, while have easily eaten a very clean diet while living alone and / or when I’ve slept alone the night before.
    I’m typing this before 6am as I listen to him snore in the next room, loving him and resenting him at the same time, and have come to the conclusion I can’t sleep beside him anymore. I feel sad about this, as it feels like a bad relationship if we don’t sleep together…. Such is the stigma…. :(
    This is not a sex thing. It’s a simple need to get some goddamn rest!

  3. You didn’t come to the obvious – that most mammals sleep together for protection and shared body heat? So obvious is the evolutionary trend.

  4. This is strange..but i guess we are all different..:) I sleep very well with my partner lying next to me, so does he! Infact I pretty much judge a new relationship by how well I can sleep with him. For me, it is a lot more important a barometer than sex is, coz sex can get better with time, but the kind of security you feel with the other person, doesnt change overnight. N it is not always a logical thing, I am not sure of my reasons for feeling safe enough to fall asleep next to a guy, not that it bothers me.

    • Cause you are a woman!!!!!!!

      • Um not exactly the reason. I’m a woman and I hate sleeping with anyone. You can’t sleep! You are constantly woken up by the other person whether they are in your space, touching you, or keeping you awake from the start. Funny thing is that if my child sleeps with me, I have no issue. Caveat: my children don’t move around, kick me or anything else. They crash out hard. But they never are in my space, trying to be up on me. Many of my women friends, actually all the women that I know now that I think about it, hate sleeping with their mates because they never get any rest.

  5. Interesting ideas on the difference between women and men in their sleep preferences. Biologically it might make sense that women feel safer with someone by their side (man or woman), but this doesn’t account for children — male or female — who always seem to want to sleep with their parents in order to feel safe.

  6. So true and like your style of writing…

  7. To me, there is nothing more relaxing than the sound of another’s heart beating. My sleep may be lighter with a partner, but I’m so much more relaxed that I am better rested in the morning.

  8. I’ve been with my husband for 4 years and before him I never got a full night’s sleep. Even in high school I would lay awake at night watching TV and reading because I just couldn’t sleep. During my drinking years that was great because I could get 4 hours of sleep after being out all night then go to work in the morning like I’d slept all night.

    Now is totally different. I still struggle with insomnia in times of great stress (two kids and a tight income do that) but I would say my husband and I are extremely compatible sleep partners. First of all, he can lay in bed and just drop to sleep in the blink of an eye. Other than finding it annoying because I usually take 10 minute to drift off on most nights, I love how wacky our conversations get when he’s suddenly half asleep and talking about his dreams. We sleep back to back a lot, neither of us likes cuddling in our sleep much and I’ve always been the type to sleep right up against the edge of the bed. He sleeps hot and half the time I do too so we almost never struggle over covers. The only sleep issue we have mutually is the obvious desire for a little more space. Every time we stay in a king size bed hotel room, it’s best night of sleep we get. It’s like a twin bed for two.

    As far as couples who both struggle to fall asleep, the author and his girlfriend in particular, shut off your phones, computers and TVs. Those are murder on your sleep cycle. Reading for 30 minutes for bed helps a ton. We also work out pretty regularly so dropping off to sleep after an evening workout is never an issue. Working out has the added benefit of being able to pop awake after 6 hours of sleep absolutely bursting with energy.

  9. Stephanie says:

    I think the reason that men and women sleep differently when bed sharing boils down to an evolutionary stand point. Women are mother’s and when carrying for our very young often bed share with them in order to protect them and also be available to tend their nightly needs. Men on the other hand are the protectors, when they have spouse/children in the bed with them they have whole other lives besides their own to look out for, so they become alert and sleep lightly until the other has left the bed to go about their day. I could be way off base, of course, but this is what came to mind as I read this.

  10. I’m a woman and I don’t like to sleep with my boyfriend in the same bed. I love him very much but we have very different sleeping styles and I can’t sleep when we are in the same bed. My friends and family say “I need to change that about me or then my relationship will fall apart”
    Why? If we spend all this quality time together when we are awake? Why do we have to be happily together when we are not even conscious?
    Sleeping is for health and a process needed to rest and replenish energy, it is and individual process. Why society keeps thinking that a couple needs to sleep together to be “close” “connected ” and etc etc??
    Am I going to be perceived as crazy and not fitted for marriage because of this?


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