Sometimes, I struggle to fall asleep at night. I would lie in bed all night, trying to stop myself from thinking about anything specific. And during these times, there was always an impulse to get my phone and browse news or SNS. I would always have to struggle for a few minutes against this idea.
There is abundant neuroscientific evidence that evening use of light-emitting devices (LEDs) suppresses melatonin and increases alertness. LEDs produce enhanced short-wavelength light emissions when displaying texts. As a result, the latency to fall asleep prolongs, and the amount of REM sleep decreases. Evening use of LEDs thus leads to poor sleep quality. In a 2015 study published in the Proceedings of the National Academy of Sciences, researchers compared the effects of reading an eBook on a LED with reading a printed book in the hours before bedtime. It was found that, compared to those reading a printed book, subjects reading an eBook took significantly longer to fall asleep, had delayed timing of their circadian clock, and lower next-morning alertness.
Notably, early pubertal children, namely 4-6th-grade elementary students, are particularly sensitive to evening light and show sleep disturbance after using LEDs before bedtime. Frequent usage of LEDs before bedtime impairs their alertness, attention, and learning efficiency the next day. Indeed, it has been reported that high school students who text longer at night after lights are out sleep fewer hours, are sleepier during the day, and have lower academic achievement.
Avoiding the use of LEDs before bedtime is essential. These findings also suggest that healthy sleep habits are important for optimal performance during the day time. In my new book written for pregnant women, The Seed of Intelligence: Boost Your Baby’s Developing Brain through Optimal Nutrition and Healthy Lifestyle, I summarized twelve strategies that help optimize sleep. I share them with you here:
- Establish more regularity and consistency in the timing of daily activities, especially the timing of getting up, evening meals, and bedtime routine. For example, you may want to read, take a hot shower, and then go to bed. Higher levels of regularity in behavioral rhythms are associated with better sleep outcomes, lower depression, and improved health.
- Make your bedroom quiet, cool, and dark, and your bed comfortable to promote sleep.
- Use your bedroom only for sleep, do not work or watch TV or videos in bed. This helps to establish a conditioning between your bedroom and sleep.
- Nap early, keep it short and before 5 p.m. Regular napping has been associated with enhanced mood, reduced risk of cardiovascular diseases and better cognitive functioning; but late napping may interfere with night sleep.
- Avoid caffeine, alcohol, and nicotine for three to six hours before bedtime, as these chemicals interfere with sleep.
- Avoid heavy meals 2–3 hours before bedtime. Eating big or spicy meals may cause discomfort and interfere with sleep. If you feel hungry, try a light snack at least 45 minutes before bedtime.
- Consume enough drinks during the day, but balance it before sleep so that you won’t wake up thirsty nor have to go to bathroom in the middle of
- Do not use light-emitting electronic devices such as cell phones and tablets before bedtime, as it has negative effects on sleep.
- Exercise every day, as regular exercise improves sleep quality. But try to avoid vigorous exercise within 2 hours of going to bed, for vigorous late-night exercise may produce increased arousal and prolong your sleep onset latency.
- Try to reduce total sitting time and time spent television viewing. The more total sitting time and time spent viewing television, the greater odds of long sleep onset latency (≥ 30 min), waking up too early in the morning and poor sleep quality, and the higher risk for obstructive sleep apnea.
- If you can’t fall asleep after 20–30 minutes, get out of bed, go to another room, and do something relaxing, for example reading or listening to slow, soothing music until you are tired enough to sleep.
- Don’t stare at your clock at night. It actually increases stress and interferes with sleep.
There is a general belief that certain food may improve sleep quality. I’m now reviewing the scientific evidence and will share with you the result soon.