Opinion on Sleep Medication

I am someone who is on medication for chronic headaches. My medication is also used as an anti depressant and as a sleep aid. I have to take it right before bed. It creates drowsiness. Because we are learning about sleeping. My Question is why do people take sleep aids? or How does the sleep aid help people? Do any of you believe that a sleep aid helps with the bodies chemical balance? In my opinion the aid does help me. If I don't take my medication I do not usually get a good nights sleep. I think I will test it in my sleep study for this class. one week I will take it another week I won't take it. Lets hear your opinions on this.