My body clock's screwed!

Argh!! Have not been sleeping too well these past few days since returning to S'pore. Slept at super odd timings lke 5am in the morning or waking up at 3 pm in the afternoon.....or even when i tried to sleep early at 10pm, ended up waking at 4am in the morning....hmm....how the heck am I going to get back into the momentum of things?