The health and economic effects of poor sleep are gaining increasing attention, including the consequences of sharing a bed, or even just a room, with partners or children. The consequences of having a companion animal in the bed has been relatively neglected, but a new paper makes a start on filling the gap.
Dr Bradley Smith of Central Queensland University fitted five dogs and their owners with monitors to register sleep and wakefulness, collecting a week's data. Although the humans generally denied suffering ill-effects from letting their dog share their bedroom at night, Smith found the sleep was much more interrupted during periods of canine wakefulness than when the dog was asleep, indicating the dog was waking them up.
The owners in the study, all women, were woken both to let their dogs out to urinate and by restlessness – dogs' sleep cycle is very different from humans and they averaged 20 percent of the night awake.
Nevertheless, Smith isn't trying to shake people's desire to keep their pets close at night.
“People are getting more benefits out of co-sleeping than negatives, so they ignore being disturbed,” he told IFLScience. Participants described feelings of security and protection, as well as just enjoying the dogs' closeness and warmth.
Frequently people seem barely aware of their dogs' effect on them. Most participants rated their sleep quality as good, probably because Smith's monitors revealed they usually went back to sleep fairly quickly after being woken up. Impacts were so light people often didn't mention getting up to let the dog out when asked about sleep quality.
Moreover, Smith noted, many dog-owners have little choice in the matter. “Sometimes it is easier to have the dog in the bed than it scratching at the door all night,” he said, although no studies have compared the two. Smith adds that puppies used to accompanying their human to bed are hard to displace. “Once you have co-slept with a dog it is very hard to stop,” he said.
Given the small, and possibly unrepresentative, sample, Smith said he “can't make blanket statements” about people who co-sleep with their dogs. The findings are reported in Anthrozoos, where the research is described as “an exploratory study”. However, with approximately a quarter of the population co-sleeping with a pet, and the enormous benefits provided by even small improvements in sleep quality, Smith hopes to expand the research to in search of helpful hints.
Besides investigating much larger sample sizes, Smith would like to know how new partners can best integrate themselves into a bed already part-claimed by a dog. He's also interested to investigate co-sleeping with cats, an unstudied topic he describes as the “next frontier”.