Research has shown that during the evening hours, it is important to avoid exposure to wavelengths of blue light to allow for the healthy regulation of our sleep/wake cycles (circadian rhythms). Blue wavelengths of light are emitted from televisions, computer screens, cell phones, blue LEDs on your stereo equipment, and from fluorescent light sources. Exposure to these sources of light, even in very small amounts, can suppress the natural production of the neurotransmitter melatonin, which encourages deep sleep through the night. In a bedroom setting, then, some dimmable incandescent or halogen sources are recommended. Remove or conceal items that emit blue wavelengths of light in the evening hours. If you like a nightlight, use a red LED. Red wavelengths have the least effect on altering melatonin production.