Research suggests that higher sleep quality is associated with greater muscle strength, and other data suggests that sleep hygiene is just as crucial to performance as physical training. Sleep deprivation can also result in a reduction of IGF-1 (insulin-like growth factor), which helps regulate muscle protein synthesis. While 7-9 hours of sleep is generally sufficient, experts warn that a one-size-fits-all is ill-advised, as sleep recommendations for optimal muscle recovery may be sports-specific.