Switch to herbal teas or to other energy boosters like ginseng, ginger, and licorice. At night, use calming herbs like valerian, hops, and passion-flower. We all have certain inborn circadian rhythms. Our body clock, our temperature, and the fluctuation of certain hormones seem to respond to the rhythm of the day, and of light. In fact, we have a gland in our brain, the pineal, which seems to respond specifically to the absence of light by releasing a hormone called melatonin.
Sunlight inhibits melatonin.
When circadian rhythms are forcefully shifted, our body tries to adapt, but it is not always successful. Melatonin production may veer out of control, and the body clock may become so disrupted we have trouble sleeping. A common form of this that most of us have experienced is jet lag. We may feel groggy, disoriented, irritable, or depressed. The most difficult schedule for the body to adapt to is a changing work shift.