blue light and insomniaA new study published this week is just in time as teens head back to school. These teens are spending extended periods of time on their computers and smartphones. The light from these bright screens, particularly blue light, is very effective at preventing the release of melatonin. The pineal gland normally releases melatonin a few hours before bed but if you have enough blue light exposed to the eye, the gland can stop releasing melatonin. As a result, it takes longer to fall asleep, there is reduced evening sleepiness, a postponed circadian clock, and reduced next-morning alertness.

Melatonin is necessary for the circadian regulation of sleep. Light exposure at night can prevent anyone from falling but new research from the Journal of Clinical Endocrinology & Metabolism discovered that children ages 9 to 15 in the earlier stages of puberty were especially sensitive to light at night compared to older teens. According to the research team, an hour of nighttime light exposure suppressed their production of melatonin significantly more than the same light exposure did for teens ages 11 to 16 who were farther into puberty.

As you would think, the brighter the light, the more melatonin was suppressed. However, small amounts of light at night can still be enough to affect sleep patterns. Students using tablets and computers or watching TV are pushing back their circadian clocks. This makes it much harder to fall sleep. One study found that 96% of teens use at least one form of technology within an hour before bed. This also includes avoiding those light-emitting e-readers.

Suppression of melatonin by light at night resulting in circadian disruption has been associated with sleep disturbances, increased risk of obesity and diabetes, as well as an increased risk for other serious diseases.

The use of these light emitting devices before bedtime can have powerful effect on the body’s natural sleep-wake cycle and may play a role in maintaining a sleep deficiency.

Children and their parents should limit use of screens at bedtime. In addition, it is important that people go to sleep around the same time every night. When the timing of your sleep is shifted even if the duration of sleep is the same, it’s not going to be as restorative. Also, avoid watching TV before bed. This also includes using your computer in the evening. Computer screens (smartphones and laptops) emit light in the blue part of the spectrum. This doesn’t cause a problem during the daytime, but at night, this blue light (short-wavelength) limits the production of melatonin. As a result, it disturbs your sleep-wake cycle. There are free apps you can install on your computer if you are one of those people that need to be on your computer at night that adjusts colors in a way that it reduces the stimulating effects of blue light at night. Caffeine and other stimulants can keep you up and interfere with sleep. It is best to avoid these four to six hours before bedtime. Finally, try to get your workout in earlier in the day. Exercise increases cortisol and can make hard trying to fall asleep.

By Michael Jurgelewicz, DC, DACBN, DCBCN

Source: Stephanie J. Crowley, Sean W. Cain, Angus C. Burns, Christine Acebo, Mary A. Carskadon. Increased sensitivity of the circadian system to light in early/mid puberty. The Journal of Clinical Endocrinology & Metabolism, 2015; jc.2015-2775 DOI: 10.1210/jc.2015-2775

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