I naturally wake up after 4 hours, once I have slept at night. Even I try to sleep little more, I do not fall asleep. When I had gone to bed around 10: 30, I automatically be awake around 2: 30 a.m & I end up just rolling on bed until I wake up. Again, in case if I sleep during evenings, I cannot wake up comfortably without 3-4 hrs of sleep. Even the alarm doesn't help to wake up in 1-2 hrs.