Is napping good for your health?

Monday through Friday is packed with early-morning workouts (if you can make ’em happen), late nights at the office, and extended happy hours. Is it really any surprise that by the time Saturday rolls around, sleeping in and napping are priorities one and two?

But what’s really best for your body: a consistent schedule or hitting the hay when you can? Researchers at Harvard attempted to answer this question by tracking the sleep habits of 61 students for a month.

Basically, napping is just no replacement for a good night’s sleep.

Here’s what they learned: The participants who had irregular sleep patterns—AKA bed at 10:30 p.m. one night, 1 a.m. the next, with daytime naps to make up for it—had worse grades than those who consistently got the same amount of sleep every night. (Hello, social jet lag.)

They didn’t just perform worse in school, either: The nappers also gained more weight. And since your appetite goes up when you’re getting less high-quality zzz’s, it can trigger a vicious cycle. Basically, napping is just no replacement for a good night’s sleep.

While the findings suggest that the ideal number of hours of sleep to get is seven to eight hours a night, researchers weren’t able to pinpoint an ideal timeframe. Students who snoozed from midnight to 7 a.m. on a regular basis were just as productive and healthy as those who did a 10 p.m.-to-5 a.m. thing, for example.

So if you’d rather do your workouts in the evening and spend your morning sleeping in instead of hitting that sunrise yoga class, go for it. Just make sure you don’t conk out when Netflix is on.

Okay, so you get that regular bedtimes are good for you, but what if the problem is actually being able to sleep? Here are several doctor-approved tips—and PS working these foods into your diet will help, too.