Allowing a pet to sleep in one’s bed might seem like a strange and overly indulgent modern trend, but it actually is surprisingly common and anything but new. Many indigenous societies have traditionally co-slept with their animals—Aboriginal Australians slept with dogs and dingoes, for example, for warmth and protection.

The decision is one that often divides owners. The two main arguments against co-sleeping are that the animal’s presence in the bed will cost its owner sleep…and that humans will catch diseases from the close proximity to dog and cat bedmates.

Co-sleeping with pets does indeed cause some reduction to sleep quality and quantity, but our research suggests this sleep loss is not severe. On average, it seems to be no worse than allowing a pet into the bedroom at night but not onto the bed. And while a 2011 report raised the possibility that humans could contract certain diseases from pets that sleep on their beds, this risk actually is minimal as long as pets are kept clean and healthy and receive regular veterinary care (including vaccinations and flea and tick control).

Meanwhile, the potential advantages of co-sleeping with a pet include…

Safety. Some people report feeling more secure and protected when they sleep with their pet—they know that the animal would provide a warning if anyone approached the bedroom during the night.

Companionship. Pets can be a source of comfort and companionship for their owners. The fact that many owners co-sleep with their pets is a reflection of how important the pets are in their lives. Owners who are unable to be with their pets during the day might attempt to maximize contact and interaction by co-sleeping with them during the night.

Pet contentment. Some pets become loud and disruptive when kept out of the bed at night. Allowing these pets into the bed could eliminate these problems and help everyone in the household sleep easier.