At one point in my life I worked the graveyard shift During that time my sleeping habits became adaptive to sleeping in two shifts. I would get home from work and sleep for a couple hours. Then wake up to do things that night sleepers do during the day. Shopping, family time, business calls, doctor appointments etc. I would try to sleep again from about 6 to 10. Then get ready for work.I have not worked graveyard in almost 20 years but can not get my internal clock readjusted to sleeping in one shift.

To add to that, two or three times a year I go into a phase where I will go 72 hours without sleep, sleep for three hours then go another 72 without sleep. This can last for a couple weeks before I crash and sleep for a full day and night.

I have done all of the usual meds and tests my pdoc can think of, and tried everything suggested to change my internal clock. I have reached the point that I would rather live with my sleep pattern than go through all of the "stuff" pdoc , GP and others want me to try. My standard reply now is " I am not a lab rat"