I worked the night shift for 3 years. I survived it however it did seem to really cause me to cycle faster. The best advice I have from this time is sleep, make sure you are getting at least 10 hours of sleep as this will be the biggest piece to mess with bipolar. I believe my faster cycling was due to lack of real sleep. By the end of three years the episodes were getting to be to bad and I was almost hospitalized so I decided it was time to come back to normal hours and since then things have been much calmer and routine.