A young ER doctor came in to see us because he works the night shift, and found that he was having trouble 
getting enough good quality sleep, and also being alert enough during his shifts.
He worked four or five night shifts in a row and then he had several days off. And his goal was to work 9 pm to 5 am for four days and then switch to sleeping from 10 pm to 6 am.
Not surprisingly, the idea of flipping night and day every few days wasn’t working. His body clock was never sure whether it was day or night.
You really can’t change your body clock by more than a couple of hours a day.
I suggested that he try the following –
- When working – At 5 am (when he was going to bed) take melatonin to help his body recognize that it was time for sleep. Sleep from 6 am to 2 pm. Keep the room dark and very quiet (use blackout curtains) and also consider getting a room air conditioner (cool air can be an important cue to go to sleep). At 2 pm get bright light. Go to work. Do this every day he worked.
- On the first day after working – sleep from 6 am to 12 pm. At 12 pm get bright light. At 2 am take melatonin. Go to sleep the first night after work at 4 am.
- Second day after working – sleep from 4 am to 11 am. At 11 am get bright light. At 12 am (midnight) take melatonin. Go to sleep at 2 am.
- Remainder of the days not working – Sleep from 2 am to 10 am . At 10 am get bright light. At 12 am (midnight) take melatonin. Go to sleep at 2 am.
The idea was to allow him to be awake for most of the daylight hours without trying to change his body clock too much.
Melatonin and bright light were used to help his body establish and maintain good circadian rhythms so he was sleeping well and alert when he was supposed to be.
Information about bright light and melatonin can be found at this webpage (we recommended a dose of 5 mg of immediate release melatonin and 30 minutes of bright light).