If you’re getting any exercise at all into your day, that’s a win. We’re all busy—work, meetings, kids, school, not to mention eating, bathing, and all of those other so-called necessities of life. We’re lucky if we even walk to the mailbox to get the mail some days.

Other days however, maybe you do find time to hit the gym or get a home workout in. But how often is that at night? After all the other commitments of the day, it’s common to want to squeeze in a late workout before ending the day.

And honestly? Good for you, if you can get up the energy after a long day to sweat—any activity is better than no activity at all.

And while that’s true, if you’re consistently working out during the later hours of the night, it can have some negative affects on the following day. Here’s why:

Working out at night can hinder your sleep

Working out past, say, 8 p.m., can negatively affect how good of a night’s sleep we get.

That’s because when you exercise, your body released endorphins, a group of hormones that makes you feel somewhat overly euphoric—a great perk of exercise when you have time left in the day to enjoy it. But an endorphin rush right before you catch your zzzs can make you lay in bed wide awake— and totally regretting the calories you just burned!

Another reason it affects our sleep? Our body starts producing the hormone melatonin, which helps regulate sleep, around 7 or 8 p.m. And experts say that fighting against that hormone to get a workout in may be doing more harm than good when it comes to getting a proactive sleep. It simply isn’t natural for our human circadian rhythms.

What if you don’t have any other time?

If the only time you can work out is during the evening, don’t think this is completely off limits. But to get the best of both worlds, it’s best to fill the time with low-key workouts, like taking a yoga class or walking on the treadmill.

In other words, don’t do an hour-long heart-boosting high-intensity routine right before hitting the sack, because then that won’t happen.

The good news? Working out at night isn’t all bad. After all, the gym is likely much less crowded during this time, so you don’t have to shuffle through crowds to get the weights you need, or wait for an open elliptical to open up, like you might have to do during more busy hours.

Additionally, if you’ve had a long day at the office, exercising can feel nice on the body—sort of like a release of stress, especially if you stick to something low-key like yoga, which can really help you unwind.

Bottom line: Work out when you can fit it in, just be wary of the affects timing could have.

Are you more of a morning or evening exerciser? Do you find working out at night causes any issues for you?