Over the past few years, a fashion phenomenon has been sweeping the country. No longer are children the only ones wearing long, one-piece pajamas. Thanks to a boom in production and nostalgia, adults across North America are jumping on board the onesie-wearing trend. From teenagers, to full-gown adults, all ages and sizes are hopping on this ever-growing bandwagon.

Even President Obama recognized the popular sleeping wardrobe style in a recent health insurance commercial.

And why not? Onesies are fun, they’re comfortable, and in the coldest of winter days, they’re incredibly warm. (Until you have to go to the bathroom and almost entirely disrobe.) Add on the ability to jump on a popular trend, and there are multiple reasons to stock up on these one-piece pajamas. (With or without the feet.) But despite all its possible perks, the PJs could bring a drawback as well: your quality of sleep.

Wearing Onesies During Sleep

One standard of falling asleep that must remain constant is comfort. If you aren’t comfortable (mentally or physically), you can’t fall asleep. Or, for argument’s sake, say you’re extremely tired and fall asleep anyway. But without the ability to relax or lay still, you certainly won’t stay asleep for long. A routine that is annoying after one night, and if repeated, can leave you cranky, irritable, and searching for any solution to your sleep-deprived status quo.

As for the onesie, most argue that they’re quite comfortable. No matter the material, they hang freely, which allows for plenty of movement when sitting or upright. When sleeping, however, much of that same comfort is lost. Because the entire piece is connected, a simple leg stretch or arm toss could mean the readjusting of the entire PJ outfit. That means, that, unless you’re ok with awkwardly-placed fabric, it just might be impossible to remain comfy without (again) readjusting. This goes double for onesies with built-in foot holders. While versions that are cut off at the ankles allow more for foot – and by extension leg – stretches, encompassing the entire foot means everything is connected to one piece of fabric. From the neck to the toes.

Sleep Quality vs. Pajamas

Obviously, if you have to keep adjusting your pajamas every time you move or roll over, it’s going to affect your quality of sleep. Not only is extra time spent getting comfortable, there is the added anxiety from not wanting to move because of it. While this may sound miniscule, mental state can have a much larger effect on sleep quality than we realize. In the same way not sleeping in one’s own bed or knowing we have to get up early can reduce the ease of sleep, knowing just how much excess work rolling over can cause brings on extra stress and anxiety. Two factors that work strictly against restful sleeping patterns.

However, there’s something to be said about children wearing footie pajamas. This has been a cultural norm for decades, and few children even complain about not being able to sleep in their zip-up nightgowns. This can be contributed to body size – with less limbs to stretch, there is less fabric to be pulled. Or rather it can be a statement of children’s ability to rest, even in a single piece of fabric.

No matter the reason, however, there is plenty of research that outlines reasons not to sleep in these uniform pajamas. While they may be ideal for lounging or staying warm on a snowy day, ultimately, they can interfere with sleep. To stay well rested through every season, opt for more comfortable, less confining sleeping clothes instead.