What Causes Short Term Memory Loss With Dull Headache?

I recently begun experiencing short term memory loss (i.e., forgetting phone conversations I have had within a six hour period, putting food in microwave and totally forgetting it was there, forgetting what I watch on TV the morning after). Some low grade headaches as well. Different from losing keys/cell phone.Sleep patterns have also recently changed due to a new eaerly morning commitment. I used to go to bed at 1-2am and up at 9-10am; now in bed around 11pm, up at 6pm daily.