The sleep-wake cycle of your body is encoded deep in your cells. Each one of your cells has a circadian rhythm, the pattern of activity that regulates the body's metabolism, and that's what makes your body feel awake or sleepy at particular times of day. Science is still uncovering new science about circadian rhythms; we know, for instance, that things like jet lag and shift work disrupt your body's circadian rhythm, because you're getting contradictory and confusing signals about when to sleep. Those are behaviors that are usually seen as unhealthy, though sometimes unavoidable, but it turns out that even some so-called healthy behaviors can affect your sleep by messing with your body's internal clock.
Disrupted circadian rhythms can do quite a lot of damage to your health as a whole, not just your sleep. Studies have linked them to higher risks of anxiety disorders, for instance — and in 2018, scientists found that a gene that regulates circadian rhythms in women can have a strong effect on some breast cancers, which might mean that night shifts and other things that mess with your body clock could increase breast cancer risk. Your sleep-wake cycle is important to more than just your rest — though when you're awake at 2 a.m. it likely seems like the most important thing in the world. Here are three "healthy" activities you probably do that are sneakily messing with your body's clock.