What's the difference between delayed sleep phase syndrome and shift work syndrome?

Causes: Delayed sleep phase syndrome refers to a tendency to go to sleep late and wake up late. Shift work syndrome refers to any problem caused by the fact that the shift that you work interferes with your sleep - most commonly because you work the night shift, a time which is when you would ordinarily be sleeping. In other words, dsps is about your "natural" tendencies, sws is due to your work.