For shift workers, the best solution isn't always an easy one. "You really have to protect that time during the day when you need to be sleeping," he says.
Those three aspects of health support each other, but Buxton says studies show that they also crumble together when any one becomes a lower priority.
"So you have a ton of job demands and you're not getting a lot of sleep. That gives you less energy for exercise," he says. "Similarly, your diet changes. Not only are you hungrier and having cravings for more food, and eating more," but being tired makes it harder to resist all the junk food you're hungry for.
Studies have shown that sleep-deprived people eat more snacks and sugary drinks and fewer fruits and vegetables.
But Buxton says there are ways shift workers can better cope.
"Ideally, you'd pick a shift schedule that's not erratic or rapidly changing from one day to the next. You know, pulling a night every third or fourth day is really brutal," he says.
With a regular schedule, say a solid month of overnight shifts, "it's easier to adapt."
The body's clock can switch to treat night as day and vice versa, but it's important to stay on that schedule, even with meals.
"Eat during your biological day," Buxton says. "Your gut is not ready for food in the middle of the night."