[This is Part 3 of a 4-part series. Click to read Part 1 and Part 2.]

When I read the Wall Street Journal stories about the supposed health benefits of sharing a bed, the study that sounded the most promising, methodologically, was described this way: “The study involved 10 young dating couples who shared a bed at least 10 nights and slept apart 10 nights for the study.” The couples were all heterosexual.

Ten is not an impressive number of couples. Still, if the researchers had randomly assigned the couples to sleep together on particular nights and separately on others, and included some solid measures of health, then they would have a nice experimental study.

Unfortunately, that’s not what they did. Instead, the couples were allowed to choose which nights they slept together and which nights they slept separately. The couples may have been in a very different mood on the nights they chose to sleep together, for example, and that mood – instead of the fact of sleeping together – may have been the actual cause of any health differences.

Let’s look at the results anyway. I’m looking for the measure of health in the journal article, but I find only these two things were assessed and analyzed (as indicated in Figure 1, if you can access the article):

  1. How “efficient” was the sleep? Participants wore devices on their wrists called “actigraphs” that measured movements.  The article isn’t all that clear, but the implication seems to be that people who moved more during sleep had more “fragmented” and less efficient sleep.
  2. What did the participants say about the quality of their sleep?

That’s it. There was no measure of health other than sleep. There were just two measures of sleep – an objective one and a subjective one.

Results for the women: Objectively, the women slept worse if they slept with their partner. Their sleep was more fragmented (less efficient) when they shared a bed than when they slept alone, and that was true regardless of whether they had sex while sharing the bed.

What women said about the quality of their sleep when they woke up the next morning was a bit different. They said that they got the worst quality of sleep when they shared a bed with their partner but did not have sex. They were equally satisfied with the quality of their sleep when they slept alone compared to when they shared a bed and had sex.

Before we go on to consider the results for the men, let’s stop right here and compare the actual findings to the claims in the Wall Street Journal. In this study, for the women, was “sharing a bed good for your health”? No, it wasn’t.

Results for the men: Objectively, all that mattered for the men is whether they had sex with their partner. If they did, their sleep was worse (more fragmented, less efficient). When no sex was involved, the objective quality of men’s sleep did not differ if they shared a bed than if they slept alone. (Not a word was said about masturbation; seems to me that should have been considered, too.)

What men said about the quality of their sleep was that it was better if they shared a bed than if they slept alone. It didn’t matter whether the bed-sharing included sex.

So far, the results for the men in this one study are as close as the data come to showing that “sharing a bed is good for your health.” Men (but not women) say that they slept better if they shared a bed than if they slept alone, even though objective measures suggested otherwise.

Do not disturb photo available from Shutterstock.