It's kind of neat to find that despite being surrounded by artificial constructions and technologic marvels we remain deeply connected to our natural environment -- we're still fixedly linked to Earth's 24-hour rotation about its axis. There are mysterious clocks inside our brain, and in every cell in our body, and those regulate not only sleep and wakefulness, but also hormones and metabolic pathways. They organize our bodily functions and behaviors so that we should be optimized for the time of day.
And messing with this governing clock comes at a price. Jet lag is an obvious example: Moving rapidly across time zones can cause fatigue, headache, irritability and indigestion. Shift work that involves a nocturnal lifestyle is associated with obesity, type 2 diabetes and heart disease.
