Horrible Sleep Pattern

My sleep pattern has been so off lately. I've gotten into the habit of sleeping from 7am-2pm (thank God my job doesn't start until 4!!) and it's not a good thing. I can't run any errands or do the things I want I to do because I'm sleeping during the day. This has happened before and it took me almost 2 months to regulate. The melatonin I take just soothes me and relaxes me, but it doesn't lull me to sleep. What can I do?! I don't want to literally sleep my days away.