Why Sleeping in Is Better for You Than an Early Morning Workout

Yeah, yeah, yeah, the early bird gets the worm and all that noise. You can point to all the studies in the world that say early morning exercise is the best thing ever, and I'll still hit the snooze button as long as humanly possible.

The truth is that sometimes morning exercise just isn't worth it. Whether you're a fully committed night owl, you had a few too many cocktails last night, or you're feeling stupid tired, you don't have to hit the gym first thing in the AM to reap the benefits of working out. In some cases, you're 100% better off prioritizing your sleep. Here's why.

Morning exercise isn't necessarily better than evening exercise

Look, there are lots of good arguments for getting up and getting sweaty first thing in the morning, including studies that point to morning exercise's metabolism-boosting, hunger-curbing benefits. But from a strictly scientific standpoint, the jury's still out on what time of day is actually best for working out.

Take, for instance, a review of 70 different studies on morning and evening exercise, which pretty much concluded "eh, whenever" regarding the best time to exercise. For almost every study that surmised morning exercise had the biggest benefits, there was an equal and opposite one that concluded evening exercise was best.

What confounds the results further is that benefits vary based on the type of exercise performed, the physiological adaptations studied, and of course, individual differences between people. All to say, sometimes morning exercise is better and sometimes evening exercise is better. Science to the rescue yet again.

The best time to exercise is the time you'll actually do it, and if that's in the afternoon or evening, fantastic. But if you're still anxiously biting your fingernails, worried you won't reap as many benefits if you hit snooze and opt for a later workout, take heart. A 2012 review found that "adaptations to training are greater at the time of day at which training is regularly performed than at other times." In other words, pick a training time and stick to it -- your body is smart and will adjust accordingly.

Sufficient sleep improves performance

Even if you're a diehard morning exerciser, the world will not come crashing down on you if you decide to skip a workout for a little extra sleep. Frankly, if you have to choose between getting a workout in or getting enough sleep, almost always you should err on the side of sleep. (Although if that means you never exercise, we should have a little chat about your other life priorities.)

The reality is that constant sleep deprivation is pretty much the best way to ensure poor performance at the gym. When you're sleep-deprived, your coordination, endurance, and perceived exertion all suffer, making exercise feel more challenging, while opening yourself up to the potential for injuries. Being sleep-deprived also whacks out your hormones, making you more likely to overeat during the day while reducing energy expenditure (burning fewer calories). Which, together, is pretty much the blueprint for weight gain.

Sleep is your body's opportunity to rest, repair, and recover from everything you throw at it. Consistently failing to get enough sleep pretty much guarantees your entire life will suffer, even if you're loathe to admit it. Darin Hulslander, a certified strength and conditioning specialist and nutritionist, says, "Sleep provides mental, hormonal, psychological, and physical recovery. It isn't just a physical need; it's physical, hormonal, and neurological."

In other words, you could actually be a better athlete and a better human being if you just let yourself have another hour or two of rest in the morning.

It's not an either/or proposition, really

When it comes to sleeping in, I'm 100% for it. I hate mornings. You will not see me at the gym before 10am. Ever.

But I'm also 100% for fitting in exercise during your day, no matter what. It's not about sleep OR exercise, it's about sleep AND exercise. The two have a symbiotic relationship where one improves the other, and vice versa.

If morning workouts just aren't for you -- great! Don't do them. Use your mornings to guarantee you get as much quality sleep as possible, then go ahead and schedule in a workout during your lunch break or after work. You, and everyone else around you, will be better for the effort.

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Laura Williams is an exercise physiologist and fitness writer who gets up at 7am ONLY because her dogs force her to. Otherwise she'd sleep 'til 9am. Connect on Twitter @girlsgonesporty and pre-order her book, Partner Workouts, on Amazon.