Recovering after your workouts is as, or even more important than how hard you work out. During the night while you sleep, your body is recovering and repairing the microscopic tears in your muscles to increase hypertrophy (making your muscles bigger). No matter how hard you work out or exercise, if you're not getting at least 8 to 10 hours of sleep per night, your body is not getting everything it can out of your workouts and exercise during the day.
Steroids merely allow the muscles to heal faster, getting the proper amount of sleep does the same thing, just not as fast xP
The pain and soreness of your muscles is a good sign, it means your muscles are healing and becoming stronger and bigger, those microscopic tears you made during your workout are healing. Getting the proper amount of sleep every night will reduce the amount of soreness and therefore increase the rate of your bodies growth, as well as the effectiveness of your exercises and workouts.
Not only does getting a good amount of sleep help your body recover faster, but it also significantly reduces your chances of becoming sick and having to skip a workout :)
Excellent reference of someone who has experimented with different amounts of sleep. Remember, this does not only apply to bodybuilders!! the exact same concept applies to even marathon runners and anything in between!!!
http://www.bodybuilding.com/fun/dean22.htm