We live in a technological era where almost every person in America owns some kind of electronic device. These devices are being used constantly and at all hours of the day and night. A recent study found that 90% of Americans use some type of electronic device a few nights a week in the one hour before they go to bed. How would you feel if you were told that this activity can have negative implications for your sleep, performance, health and safety?
A study conducted by Chang et al. at Brigham and Women’s Hospital in Boston, MA has concluded just that - that using electronics that emit light, specifically an e-Reader, before bed can in fact have adverse effects on various facets of life.
Researchers compared the effects of using an e-Reader with reading a printed book, both for about four hours before bedtime for five consecutive evenings. They found that using a light emitting e-Reader before bed decreases sleepiness, increases the time it takes to fall asleep, and increases sleepiness after awaking the next morning.
The aforementioned conditions can be explained by suppressed melatonin levels induced by using an e-Reader before bed. Melatonin is a sleep-facilitating hormone whose levels rise and fall according to each individual’s circadian clock. The circadian clock is a cycle that is responsible for synchronizing many internal physiological and biological processes. If melatonin levels are altered due to exposure to light emitting devices, the circadian clock shifts and the sleep cycle no longer coincides with the circadian cycle. This also means that in the morning, the circadian cycle is lagging behind which causes melatonin levels to be higher than normal resulting in increased sleepiness.
Recent evidence has led to the concern that chronic suppression of melatonin levels by nocturnal light exposure can be linked to an increased risk of various diseases such as breast, colorectal, and prostate cancer. It is also conceivable that continuous use of a light emitting electronic device before bed can lead to increased risk of developing a sleep disorder and/or sleep deficiency.
1. Chang AM, Aeschbach D, Duffy JF, and Czeisler CA. Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness. PNAS, 112:4 1232-1237 (2014).