To sleep, perchance

PITY the poor pineal gland, tucked behind the thalamus in a gap between the brain's hemispheres. It has a simple task--to make melatonin, a hormone that regulates sleep. In days gone by, it would start doing so after sunset, ramp up to a maximum in the middle of the night, and then taper off toward the morning. The result was regular, dependable periods of sleep and wakefulness. Modern life, though, is confusing for the pineal because its signal to start work is the absence of light--specificall...