Do you have the habit of reading on your iPad or mobile phone before going to bed? If so, your sleep quality may have dropped unconsciously.
In recent years, the use of electronic equipment has increased greatly. some kind of electronic device within an hour before going to bed at least a few days a week.
Ａt night has a series of negative effects on sleep, including inhibiting melatonin secretion, reducing drowsiness, increasing the time it takes to fall asleep, and making users feel more tired when they wake up in the morning.
Do you have obsessive-compulsive disorder of staying up late and playing with cell phones and iPads before going to bed?
In the experiment, the researchers recruited 12 healthy young people (6 men and 6 women) to complete the 14 day in-hospital study. During this period, participants were asked to sleep for eight hours between 10 p.m. and 6 a.m., a habit that lasted three weeks before they took part in the study. Then, the participants were asked to read according to the following two scenarios:
Before going to bed for five consecutive nights, use a self luminous e-book reader (such as iPad) for about 4 hours in dim light before going to bed;
For five consecutive nights, under the same lighting conditions, read paper books for about 4 hours.
“We didn’t test whether using a light-emitting e-book during the day would affect sleep,” Zhang told the scientists. However, according to previous studies on light exposure at different times during the day and at night, the effects of using these devices during the day on sleep and circadian rhythm may not be the same as using them at night“
In the course of the study, the researchers measured the participants’ sleep related indicators, including melatonin level, sleep latency (the time between turning off the lights and the beginning of sleep), total sleep time, sleep efficiency (the proportion of sleeping time in bed) and EEG. Participants were also asked to assess their subjective sleepiness.
Reading a glowing e-book before going to bed has many disadvantages
“Melatonin, a hormone that promotes sleep, usually rises before bedtime,” Zhang told us; In the study, we found that the use of light-emitting e-books before bedtime inhibited melatonin. At the same time, our study shows that the secretion cycle of melatonin will be delayed
When reading self luminous e-books, melatonin began to secrete more than 1.5 hours later than reading a paper book, which may increase the risk of sleep cycle delay disorder and insomnia, especially for those who can decide their own time to sleep and wake up.
At the same time, compared with reading a paper book, participants who read Le eReader before bedtime spent an average of 10 minutes getting to sleep, and their REM sleep period was significantly shorter.
In addition, the results showed that participants who read self luminous e-books one hour before bedtime rated themselves less likely to sleep, and their EEG showed that the energy of brain waves related to sleepiness decreased. “We also found that participants who used self luminous ebooks before going to bed were more sleepy when they got up the next day,” Zhang added What’s more, they need longer to be fully “awake” and reach the same level of alertness.
The root of the problem is still blue light
The researchers examined all-optical spectra of light emitted from self luminous e-books and reflected light from paper books.
The results show that most of the light emitted by these e-books is short wavelength light, and its peak is 452 nm, which is located in the blue light range; The paper books reflect a broad spectrum of light (white light), with a peak at 612 nm. In addition to the Kindle, the light emitted by electronic devices such as iPad, iPad 2, iPhone, iPod touch, kindle fire and nook color are rich in short wavelength light.
“Non self luminous e-books like the Kindle are unlikely to have a negative impact on sleep, which is similar to that of paper books,” Zhang said
“Studies have shown that short wavelength light can more effectively inhibit melatonin, phase shift the secretion cycle of melatonin, and increase people’s alertness,” Zhang explained But the researchers also pointed out that although the short wavelength light emitted by self luminous e-books may have a negative impact on sleep, considering that electronic devices emitting longer wavelengths were not used in the study as a control, these negative results may also be caused by differences in the luminous level of the devices.
It is worth noting that reading a paper book reduces the time taken to fall asleep by 10 minutes, which is similar to the effect of using ezzopiclone in patients with primary insomnia.
Previous studies have found that blue light has the greatest negative effect on hamsters’ emotions, and these results may also apply to humans.
Finally, Zhang said: “according to the research results, in order to avoid the impact of self luminous e-books on sleep, it is better not to use such electronic devices within a few hours before going to bed. Those non self luminous electronic devices may be better choices. However, we did not test such devices in this study. Further research is needed on the effects of light-emitting devices on sleep and health, and there may be longer-term effects that we have not yet considered. ”
Spectral radiometric comparison of self luminous e-book (gray) emission light and paper book (black) reflected light.