One of the most essential components when it pertains to muscle building (& weights loss, but that's for another conversation) would be muscular growth. Recuperation when it comes to fitness is the body's ability to recover muscle tissue and replenishing energy stores after exercising.
Sleep and nutrition is what I'd call the "perfect marriage". When giving the body the appropriate amounts of protein, carbohydrates & fats, in conjunction with a good rest schedule, it will accelerate the recovery process, which will essentially build quality muscle as you continue on with your strength training routine.
How much rest, you'd say? The answer? Everybody is different. To test how much rest you need each day you'll need to conduct an experiment: pick a day that you'll have a open morning the following day & work out at a time that best suits you in accordance to your schedule. Rest at a reasonable time without setting the alarm clock. When you wake up count the hours you rested without much interruption. Record these numbers for 3 consecutive days. You'll start to notice a pattern; whether it's 7, 6, or 8 pick the middle number and attempt to meet that range each night you rest.
Of course, it will be easier said than done considering work schedules, school, etc. On the other hand, if done on schedule with a consistent workout and nutrition regimen, it is highly likely you'll get your results a lot effectively then only limiting 4 (or for some of you, 3) hours of rest at night. Studies have shown the average American rests about 5 hours a night, which some may consider not enough.
Most importantly, our body has a unique recovery response time post-exercise, and nutrition plays an important role in the process. In general, it is ideal to rest between 6-8 a night to guarantee a speedy recovery process in between workouts. Prioritize these elements into your routine in order to achieve success in your goals and beyond.