About half of all pet owners let their companions sleep with them in bed at night despite a common belief that co-sleeping with your dog or cat may interrupt your sleep. But is that belief grounded in science? In short, it depends. Surprisingly, there isn’t a lot of reliable research in this area, given how many millions of Americans share their bed with their furry friends. Still, the research suggests that any possible adverse effects from sleeping with a dog or cat are modest for most people. However, there are some exceptions.

For example, in a small survey from 2015, about one in five pet owners whose pets slept in their beds said the pet was disruptive to their sleep, but twice as many said their pets didn’t bother them and made them sleep better. A similar study from 2017 took a more scientific approach and measured the quantity and quality of sleep that both people and their pets got while sleeping in the same bed or bedroom. The human and canine participants wore accelerometers to assess their sleep every night for a week.

People whose dogs slept in the same room but didn’t share a bed with their pet got about as good a night’s sleep as the average person, remaining asleep for about 83% of the time in bed. (An average healthy amount is 85%.) Those whose dog shared their bed had slightly less efficient sleep, but not by much, remaining asleep about 80% of the time. That translated to about 14 minutes of lost sleep for those whose dogs slept in their bed, possibly a worthwhile tradeoff for those who believe they benefit from the comfort or security of sleeping with their best friend.

A more recent study conducted only in adolescents found that about a third of them slept with their pets sometimes or frequently, and the quality of their sleep was nearly identical to that of teens who didn’t sleep with pets. The adolescents who frequently slept with their pets had the best sleep quality overall, by a small amount, but took longer to fall asleep than those who only sometimes slept with their pets.

Sleeping alongside each other can also strengthen the bond between pet owner and pet, which is never bad for the animal or human. But that’s only the case if humans get the sleep they need. If your pet snores or frequently moves, such as during dreaming, that could disrupt your sleep and might be a good reason to kick them out of the bedroom if you can. According to a New York Times interview with Alexandra Horowitz, author of Inside of a Dog: What Dogs See, Smell and Know, it’s tough to break the habit of sleeping in the same bed once you allow them to experience the luxury. But there’s also no evidence that letting them sleep with you can lead to behavior problems, she says, so it’s a matter of what works for you.  

When Sharing a Bed With Pets Isn’t Wise

As much as you might love your pet, sometimes it’s best for your health if they aren’t sharing your bed. For example, people with asthma, COPD, or allergies may find that sleeping with animals can worsen their condition, even if their pet doesn’t shed. This is because allergens exist in more than just dogs’ and cats’ fur. They can also be in the animal’s skin or saliva.

If you’re among the approximately 30% of Americans who have insomnia, you don’t need one more complicating factor that could interrupt your ability to fall asleep or stay asleep. Similarly, those with obstructive sleep apnea, including at least 25 million Americans, would be wise to sleep without their pet curled beside them as well. This is particularly true if your pet is a chewer; you don’t want them gnawing on your CPAP machine parts.

Suppose your dog is still a puppy or your pet is otherwise new to the house, such as a recent adoptee from a rescue organization. In that case, it’s crucial that they first get used to your home and learn appropriate behavior before you bring them into your bed. For example, puppies and new dogs need to learn that their kennel is a safe place to go when they’re frightened or anxious.

It also matters what kind of animal we’re talking about. While sharing a bed with your dog or cat is generally okay, people with other pets, except perhaps the occasional pot-bellied pig, are best leaving them in their enclosure. Ferrets, guinea pigs, gerbils, hamsters, rats, chinchillas, and rabbits all need to be sleeping in their bed for your and their safety. For example, these animals are small enough to be accidentally crushed by you in the middle of the night. Likewise, leave your snakes, lizards, parrots, and other exotics in their enclosures at night.