Shift work is defined as staying awake for 2-3 hours between 10:00 p.m. and 5:00 a.m. for 50 days a year.

“if you stay awake for two or more hours during your habitual sleep time and when they say habitual sleep time they assume that we are just like you said we are kind of programmed to slave somewhere between say 10 pm and then stay in bed and kind of wake up after 5am so the idea is if you stay if you're staying awake for two or more hours between 10 pm and 5 am and you are engaged in some activity whether it's physical activity or intellectual activity you are not lying in bed and wondering worrying about something but actually working so that defines that's defined as shift work”