Should you work out if you haven’t gotten enough sleep? A study published earlier this year gives a good, real-world look at the question, finding that people who habitually got five (only five!) hours of sleep were able to make good gains while strength training with resistance bands. I’ll dig into the study a bit more below, but first let’s cover the basics.
How much sleep do you need for muscle growth?
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A healthy lifestyle should include a healthy amount of sleep, which will be somewhere between seven and nine hours, depending on the person. If you exercise a lot, that may add to your sleep need; it’s not unusual for athletes to sleep nine to 10 hours.
When it comes to muscle growth specifically, there’s no definitive number of hours needed. Exercise science researcher Brad Schoenfeld, who posted about the new study on Instagram, mentioned in the caption that there probably is a minimum amount of sleep we need for gains, but “exactly how much isn’t clear and likely would be specific to the individual.”
In other words, science can’t answer this for you quite yet, but you probably can’t get by on way too little sleep. Seven hours is probably fine. What about five? That’s what the study looked at.
Can I still build muscle on five hours of sleep a night?
Yes, most likely! The recent study is, of course, not the be-all-end-all answer to the question (no study ever is), but it gives strong evidence pointing toward five hours a night being probably fine.
You can read the full text of the study here. The participants were men who did not usually do any strength training, and they were excluded from the study if they had any diagnosed sleep disorders. The 36 men were divided into three groups: a group that averaged seven hours of sleep per night, a group that averaged five-ish hours a night, and a control group that averaged more than seven hours a night.
The control group did not exercise in the study. The seven-hour and five-hour groups did. (Perhaps we can think of the control group as the “what if I slept in instead of hitting the gym?” group.)
The results? For some muscle groups, the seven-hour group got slightly better gains than the five-hour group, but for others they were roughly even. Both groups gained more muscle than the non-exercising control group. The authors write: “the results of the present study suggest that the value of 7 hours as a minimum night sleeping time can be relaxed when it comes to a recuperative state related to muscle strength performance.”
The study has its limitations, including the fact that it was all men, that they used resistance bands instead of barbells or dumbbells, and that the subjects were untrained to start with (making it easier for them to grow muscle). But the results match up with what pretty much any trainer or fitness enthusiast could tell you: A full night’s sleep is great to have, but not essential to making progress in the gym.
Consistency matters more than getting the details right
How can this be, if rest is important to muscle growth? Well, for one thing, rest isn’t a magical spell that needs to do its work uninterrupted. (You don’t even need full rest days if your workload is managed appropriately, but that’s a whole ’nother conversation.)
But ultimately, the big lesson every experienced gymgoer wishes they could impart to every noob is that getting most things right, most of the time, beats the pants off of occationally getting everything to line up perfectly. If you only lift when you’ve had a good night’s sleep, you may not end up training as much as you’d like. Prioritize consistency—making it to the gym whenever you can—and you’re in a much better place to realize those gains.