It's a polarizing topic: should Fido be allowed to sleep on the bed, or is that a recipe for a poor night's sleep for their humans?
It turns out snoozing alongside your pooch doesn't disrupt your sleep as much as you might think, according to research from the University of Toronto Mississauga's department of anthropology.
For the study, researchers tracked nighttime activity of humans and their dogs using wearable monitors. They found human movements were more than twice as likely to precede dogs' activity than the other way round - suggesting people may disrupt their canine companions' sleep more often than be disturbed themselves.
The findings, published in PLOS One , suggest that while human and dog nighttime activity are correlated, there appears to be a disconnect between how owners thought they were sleeping and how well they actually slept.
"I would say my dog disrupts my sleep. But it's really interesting to know that maybe that's not actually the case," says PhD student Lavania Nagendran, who led the study alongside Ming Fei Li, a doctoral alum of the department who is now a postdoctoral researcher at Duke University.
For the study, 25 humans who owned one or more dogs - totalling 38 - wore an actigraphy sensor (a type of accelerometer) on their wrist in bed, while the dogs wore the devices on their collars. Data were obtained across four weeks.
Participants also filled out surveys, which provided an understanding of how co-sleeping made owners feel, offering researchers insight into owners' subjective assessments of their own sleep.
The data showed a detectable relationship between human and dog activity in 61 per cent of co-sleeping pairings, highlighting the deep connection between the species.
However, in 45 per cent of those cases, human activity preceded dog activity - for example, if a human moved in their sleep, their dog would move shortly after - compared to only 18 per cent of cases in which dog movements preceded human activity.
The research also found co-sleeping with one or multiple dogs did not disrupt objective sleep, despite owners with multiple dogs reporting poorer subjective sleep quality.
For Nagendran and Li, the study's main takeaway is that humans and dogs are deeply synchronized with each other.
"We're sharing our space and we're sharing our routines. More often than not, we're creating the routines that we have for our dogs and vice versa," Nagendran says. "Our findings show that we're very much in tune with one another, especially during the nighttime."
She adds that this natural synchronization, backed by the paper's data, shows dog owners that they don't necessarily have to change their routines or habits.
About 72 per cent of participants reported feeling safer having their dogs with them as they slept, the study indicated - a theme that Li says she has observed in other research.
"Thinking more broadly in terms of our shared evolutionary history, we do think this enhanced safety serves a function to bolster our bond with dogs," Li says.
The researchers note all the dogs in the study were huskies and malamutes with no health problems, so the findings may not generalize across all breeds. "However, by accounting for breed-level differences, which is seldom done in other human-dog co-sleep studies, we are better able to assess variables of interest," the study states.
Looking ahead, the researchers say they would be interested in a future study that compares human-dog pairings with humans who don't own dogs.
"There's a very special close bond at play here," says Li. "We're lucky to get to study it."
