Not all sleep is equally useful for recovery
Sleep runs through repeating stages, and they play different roles in physical recovery. Deep slow-wave sleep (the stage where you're hardest to wake up) is when most growth hormone gets released and physical tissue repair happens, including muscle protein synthesis. REM sleep, where dreaming happens, is mainly tied to cognitive recovery, memory consolidation, and emotional regulation.
Deep sleep makes up a bigger share of the night earlier on and gradually decreases toward morning, while REM sleep does the opposite, increasing closer to waking. That means for the same total sleep duration, going to bed earlier after a hard physical workout can net you more restorative deep sleep than going to bed later with the same time in bed.
Practical takeaway: it's not just total hours of sleep that matter, but its structure — a consistent bedtime and getting enough uninterrupted sleep (not cut short by an alarm early in the cycle) directly affects how much real physical recovery you actually get out of a night's sleep.