A stint in the great outdoors improves sleep

Greater exposure to sunlight by living outdoors and eliminating electric lighting at night resets the biological clock, they said after an experiment with eight adults.

A typical modern environment causes an estimated two-hour delay in circadian cycle, as measured by melatonin, but living with only sunlight and campfire light (no torches were permitted) may increase alertness in the morning, said the researchers from a sleep laboratory at the University of Colorado Boulder.