Should you work out if you haven't gotten enough sleep? While you're always allowed to take a guilt-free rest day if you feel you need it, I often see people talking themselves out of a perfectly good workout because they think it will somehow be a waste of time. Fortunately, we have some science to answer the question. In that study, 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 of how sleep relates to muscle growth and strength building.How much sleep do you need for muscle growth? 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 hours or more.
When it comes to muscle growth specifically, there’s no definitive number of hours needed. Exercise science researcher Brad Schoenfeld, who posted about the study of five-hour sleepers on Instagram in 2024, 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 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 2024 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.”
