Depression can have an affect on your sleep schedule. I know for me, when I am really down, there are some nights I have trouble sleeping. Or if I do fall asleep, I will often wake up often through the night. I toss and turn sometimes and that bugs me. I know depression will keep me up in the morning when I want to sleep in.
But yeah, getting a good nights sleep is ideal to our brain health. Not getting enough sleep can cause problems with your day to day life. I know I have had trouble working when I can't get any sleep.