Sleep science largely focuses on individual sleep behaviour. But how do bed-partners influence your sleep quality?

An estimated 60% of us share a bed with someone else. It’s considered as being totally normal. But is it time to reconsider this ‘norm’ for the sake of our own health? Not to mention our partners? Scientific research says maybe we should.

As humans, we will all spend around a third of our lives asleep. Or at least try to. According to the National Institute of Neurological Disorders and Stroke in the United States, about 60 million people a year report suffering either long-term or occasional sleep disturbances. That’s nearly one fifth of the entire population of the US.

So it’s not surprising that a large amount of money is spent not only on sleep research, but also on consumer sleep products. Indeed, the industry is now worth in excess of $32 billion a year.

 Are sleep researchers missing the obvious?

But this paradigm of research and expenditure often misses a crucial point. People don’t sleep alone. Traditionally, acquiring a sleep partner has been viewed as a rite of passage to adulthood. Despite such a drastic life change, we’re unlikely to stop and think about whether it could affect our health. However, research is starting to reveal that our sleep patterns can change when we bunk up. Indeed it may have significant effects on our lives – good and bad.

Scientific research concerning the effects of sleeping with a bed partner,  (aka dyadic-sleep), is limited, but not insignificant.

Physiological effects

Sleep studies that measure brain-wave activity or body movement, have shown that sharing a bed results in worse sleep quality compared to sleeping alone. More specifically, dyadic sleepers experience less REM sleep  and increased physical activity during the night, compared to those who sleep alone.

So does sharing a bed mean equate to poorer sleep? It’s not that simple.

Emotional factors

Despite evidence hinting at the potential harm to sleep quality, participants generally report being more satisfied with their sleep when sleeping together with their partner rather than alone.

So how can we explain such divergence between self-reported evidence and the lab results?  Researchers at the University of Utah suggest that in order to answer this question we need to understand the relationship between partners.

In 2008 Lisa Diamond and colleagues investigated what happens when romantic partners are temporarily separated. They found that some individuals who undergo ‘travel-related separations’ showed increased attachment anxiety.

Although it’s more commonly associated with young children, attachment anxiety can also have a significant impact in adulthood. And according to the researchers,  it can act impact on sleep quality during the separation phase.

Hence one possible reason that you sleep better with your partner is that your attachment leads to feelings of anxiety when you are apart.

Overall then, while dyadic sleep appears to decrease sleep quality, (using objective sleep measurements), separation from your partner actually exacerbates sleep problems because of the effects of attachment anxiety.

Syncing with your partner

But that’s not the only way couples can affect each other’s sleep quality. Apart from core sleep times, spouses may have a direct effect on sleep by acting as social time-keepers. This is because partners have an influence on both meal-times and pre-bedtime rituals during the day. These factors have been shown to have a significant impact on our internal body clock.

One study found that similarity in sleep-wake rhythms can predict the strength of a couple’s relationship. Couple’s whose sleep-wake preferences were “mismatched” were found to have worse sleep quality that those who had more similar sleeping patterns. In other words, couples who naturally wake up and go to bed at similar times have been found to be more satisfied in their relationship.

So there we have it. To have the optimum sleep, it’s possible that nothing beats that of the bachelors life. But if you are planning on moving in with your partner, it might be worth finding out about when they plan on getting up in the morning…

Further references:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2903649/
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2644899/

Benjamin Holding Author

Benjamin Holding is a doctoral researcher at Karolinska Insitutet in Stockholm, Sweden. His primary research focus is the effects of sleep deprivation on social interaction.