Health impact assessment of introducing LED street lighting in Stockport
Evidence indicates that exposure to artificial bright light during the night-time suppresses melatonin secretion, increases sleep onset latency and increases alertness. Chronic ALAN exposure can cause circadian rhythm misalignment which may have negative effects on the psychological, cardiovascular and/or metabolic functions.
In Eyes, a Clock Calibrated by Wavelengths of Light
Any sort of light can suppress melatonin, but recent experiments have raised novel questions about one type in particular: the blue wavelengths produced by many kinds of energy-efficient light bulbs and electronic gadgets.