Trouble Sleeping

I probably know more about this than cars. I too woke up at 3:00 in mornings. Often I would be very tired in the morning. My doctor suggested I wear this device that monitors oxygen levels at night. I wore the device and it showed my oxygen levels were very low while sleeping. If you're not getting the oxygen, you body forces you to wake up to breathe. Note that this test is NOT the expensive sleep over at a clinic -- although I did follow up with the clinic test.

Several people mentioned sleep apnea as a possibility. You should get tested for this.

I now use a CPAP machine. I sleep through the night and it makes all the difference in how I feel in the mornings.