Whether you lift or not, everyone needs a descent night sleep. How long is determined by the individual’s ability to function. Everyone is different. I can’t have less than 6 hours, but no more than 7 hours of sleep or I feel sluggish the rest of the day. I can’t take naps either for the same reason. Sleep is important for recovery, but is also the only time of day when toxins are removed from your brain, which is believed to be one of the causes for Alzheimer disease.