Is It Actually Healthy to Let Babies Nap Outside in the Winter?

I have to be honest: I want to be a Danish baby sleeping outside in the cold. TikTok keeps showing me videos of infants napping in strollers parked in outdoor courtyards or along sidewalks of downtown Copenhagen while Mom meets a friend inside at a cafe. Judging from the millions of views, I’m not the only one who can’t get enough. As Americans, the practice seems shocking, but also kind of… lovely. I mean, who wouldn’t want to take a snooze while bundled up all cozy in the crisp winter air?

Yet the trend has people asking, Do Danes really do this? And is it actually healthy – or safe?

I hopped on a call with Iben Sandahl, a family counselor in Copenhagen and co-author of “The Danish Way of Parenting,” to find out if these videos are legit. “Yeah, it’s a tradition,” she tells me. “I slept outside when I was a child. My children have slept outside as well.”

It’s common practice throughout Nordic countries, and goes back to the philosophy of “friluftsliv,” aka a commitment to enjoying fresh air no matter the forecast. “We have the saying in Denmark that there’s no bad weather, there’s only bad clothing,” says Sandhal.

According to Sandahl, parents typically start to let their newborns doze alfresco once they regain their birth weight, which should take a couple of weeks. Then, for as long as a child continues to nap, they’ll usually have at least one a day outside. If it’s raining or snowing, parents use strollers’ weatherproof canopies or covers to keep the baby dry. Mostly, Sandahl says, people just use “common sense,” and keep the child inside if it’s dangerously windy out or if the temperature’s super extreme. Though some parents report their cutoff being as low as 5 degrees Fahrenheit. (Hopefully it goes without saying: if you’re interested in trying this with your own little one, talk to your pediatrician first.)

Utah-based pediatrician Jonathan Williams, MD, who may be better known as the “TikTok Kid Doc” to his 573K followers, lived in Finland for a couple of years and tells me he used to see this even in the dead of winter. “I thought it was nuts,” he admits. “I wasn’t used to the cold yet, so I was freezing and then there’s this baby totally asleep in a stroller on a front porch. But culturally, it wasn’t weird at all.”

It’s not just that Nordic people don’t flinch at the idea of cold air – they actively embrace it as a way to develop immunity. “When we wake them up from a nap, we really like our children to have these red cheeks,” says Sandahl. That rosiness is seen as a sign the kiddos have been basking in a clean, healthy climate. This nearly-religious belief is so ingrained that daycares will leave a whole line of strollers out in the cold for naptime.

Scientific studies on that improved immunity, however, have shown very mixed results. “Some are like, absolutely not, and some think maybe,” Dr. Williams says, of the theory that cold outdoor air can help protect little ones from illnesses like colds. He hypothesizes that any immune benefit would likely come from spending less time in crowded indoor spaces at daycare or at that cafe with Mom. “If my kid is outside instead of inside where everyone is coughing, maybe they’re kept safe from some of that,” he says.

However, there is evidence to suggest that children sleep better outside: A Finnish study from 2008 found that some children napped for 30 to 60 minutes longer outdoors than they did indoors. Sixty-six percent of parents reported that their kids were more active and 54 percent said they ate more after outdoor naps.

Somewhat astonishingly, researchers found that the ideal outdoor temperature for restorative sleep was just 21 degrees Fahrenheit. (Of course, this assumes the child is dressed in multiple layers and a sleeping bag.) “If a parent comes to me and is like, ‘How do I improve my kid’s sleep?’, one of the things you might deal with is sleep temperature,” says Dr. Williams. “We know that you get deeper sleep in cooler temperatures, right? So maybe there’s something in that magic.”

More than worrying about any particular temperature, Dr. Williams says pediatricians are “nervous Nellies” about leaving a sleeping baby unattended because of the risk of sudden infant death syndrome (SIDS). “But as long as the sleep environment is safe, I don’t really care if it’s right outside my window,” he says. That means making sure the kid is flat on their back, has ample space to breathe, and has a monitor that the parent can check if they’re not within their line of sight. Even if you’re creating extra cold air flow by doing something like going for a run with that stroller, Dr. Williams just says, “if they’re comfortable enough to sleep, they’re probably okay.” But, he adds, “if it’s cold, if it’s my kid, I’d want a thermometer in there just to make sure.”

All that said, if someone tried leaving their baby alone on a sidewalk in New York City, the police would likely quickly show up. Part of what makes this practice possible in countries like Denmark is that kidnapping is just not a thing that happens there, says Sandahl. The 2008 Finnish study said parents reported the most dangerous situations were when squirrels, cats, or birds came too close to the stroller for comfort.

But in a peaceful Nordic setting – as long as you’re free of curious animals – nodding off in the open air could be the start of a lifetime connection to nature. “I played a lot outside, and I slept outside, and I calmed down outside,” says Sandahl. “So now as an adult, fresh air definitely means something to me.”