Is sleeping with your dog in the bed bad for your health?

Every night, a 45-pound, 3-year-old Dalmatian/Heeler mix shares my bed. We’ve had the same bedtime ritual for years: I give her a treat, she “gives me five” (with one paw), then “gives me ten” (with two paws), and then the lights go out.

Recently, however, my dog did something that made me wonder if sharing my bed with her was a good idea. We were playing outside when she cut her ear. I took her inside so I could clean her wound. Immediately, she bounded into my bedroom and jumped on my bed, smearing blood all over my comforter.

As I scrubbed blood out of fabric, it dawned on me that my dog is actually pretty gross. She plays in the dirt, chews her nails, eats cat vomit, regularly steps in poop, and drinks out of the toilet bowl. And I’m sharing my bed with her every night. Was it actually healthy for me to sleep with my dog in the same bed?

I Googled “is sleeping with your dog unhealthy?” and was met with conflicting results. Some sites said it was OK, while others advised against it. But the results were mostly from dog bloggers—not exactly a group of people I wanted to trust with my health.

So I decided to do of my own research. I called Dr. Jack Gilbert, the director of the Microbiome Center at the University of Chicago, a.k.a. the expert on all things germ-related. He told me that sharing your bed with your dog is unhealthy—but only in some cases.

For instance, you shouldn’t let your dog sleep in your bed if you’re even a little bit allergic, says Gilbert. “Your immune system is primed to overreact to the allergens,” he says, and your bed becomes an allergen epicenter. You, in turn, breath those harmful particles in for eight hours each night, and that can take a real toll on your system. In fact, a study conducted in Korea found that mice exposed to allergens for a prolonged period showed high levels of harmful inflammation.

It might sound obvious to avoid contact with dogs if you're allergic to them, but dog allergies are way more common than you think. More than half of the population has allergies, and more than a third of those are cat and/or dog allergies, according to the Asthma and Allergy Foundation of America.

The good news: I don’t have any allergies. But as it turns out, I still wasn’t in the clear.

Dogs often toss and turn at night, which can interrupt your sleep patterns or cause you to lose sleep altogether. Poor sleep is associated with everything from eating more to decreased athletic performance. People who slept just five hours a night ate more calories a day than people who slept the recommended eight hours, according to researchers at the Mayo Clinic, while pro athletes who don’t sleep enough tended to have shorter playing careers, according to researchers at the Martha Jefferson Sleep Medicine Center.

Fortunately, my dog doesn’t wake me up at night, so I wasn't at risk of experiencing negative health effects from lack of sleep. In fact, I suspect my dog helps me sleep better — and when I did a little bit more research, it turned out that I’m not alone. More than twice as many people say their dogs help them sleep than people who say their dogs disrupt their sleep, according to a study published in the journal Mayo Clinic Proceedings.

That might be because pets have positive effects on psychological and physical well-being, which helps shape how we regulate our emotions and deal with stress. Researchers at the University of Missouri-Columbia discovered that interacting with your pet causes your brain to release oxytocin, the “feel-good” hormone. In short: Pets keep you chill. The greater the bond, the stronger the effect.

But what about all of those gross germs I was worried about my dog bringing home? Turns out, they might actually be good for me. Dogs raise the bacteria count in your house, according to researchers at the University of Colorado. But not all of that bacteria is “bad.”

In fact, exposure to many types of bacteria can help bolster your immune system, which can help you fend off disease, and even help you maintain a healthy weight and good mood. Dr. Gilbert, for example, says he conducted a study that found kids who grew up around farm animals had lower rates of some autoimmune diseases. He says having a dog close to you in the home is the next best thing.

That’s why my dog will stay in my bed for years to come. Besides, she wouldn’t have it any other way.