In the late 1990s, smartphones started appearing in the market. For many people, it's the answer to their productivity woes but for some, it marks the beginning of their sleeping problems. Studies have it that exposure to blue light, the light emitted by electronics and energy-saving light bulbs, at night can affect sleep quality and quantity.
Based on statistics, many of us are sleeping less than the previous generations. About 31% of us sleep less than six hours at night while 69% reported to have insufficient sleep. This phenomenon happens not because many of us chose to wake up earlier; it has something to do with what we do before we sleep.
While there are several factors that can disrupt normal sleeping patterns, the use of smartphones and other electronic devices contributes to the growing problem on sleep deprivation. These devices have higher concentration of blue light than natural light. Compared to other wavelengths of light, it's the blue light that is shown to disrupt sleep due to its effect on the sleep-inducing hormone melatonin.
Melatonin and the Human Circadian Rhythm
Melatonin is a hormone produced by the pineal gland in the brain. The secretion of melatonin depends on the light signals received by suprachiasmatic nucleus (SCS). When SCN is stimulated by daylight signals, it triggers the pineal gland to suppress melatonin production. Then, at night time, when SCN stimulation on the pineal gland is less due to absence of daylight signals, melatonin production increases.
The hormone melatonin plays an important role in sleep. It helps regulate the body's natural 24-hour clock or the circadian rhythm. It is the circadian rhythm that dictates when we sleep and when we wake up. Hence, disruption in the secretion of melatonin can affect the circadian rhythm and consequently, the quality and quantity of sleep.
Effects of Blue Light on Melatonin Secretion
As early as 1950s, studies have been done to determine the effects of the different wavelength of light to the circadian rhythm. While earlier studies were done on marine organisms, it provided significant insights on how blue light impacts the body's circadian rhythm.
In a study conducted by Harvard researchers, it was found out that blue light suppresses melatonin production twice as long as the green light. It also has the ability to shift the circadian rhythm twice as long as the green light.[1]
Aside from sleep disruption, studies have also shown that suppression of melatonin production can lead to obesity[2] and cardiovascular disease[3].
Consequences of Sleep Deprivation
The effects of sleep deprivation is well-documented. Several studies have shown that lack of sleep can impair human functioning, affect one's mood[4], increase the risk of obesity and diabetes[5], impair decision-making ability[6], elevate cortisol level (also known as the stress hormone), and affect one's performance at work[7].
While these studies do not suggest that you totally abandon your electronic gadgets and other blue light-emitting devices, they show that sleep deprivation has far more negative consequences than just giving you a pounding headache; hence, moderation should be observed when it comes to using electronic devices.
Here are other things you can do to achieve better sleep at night:
1. Avoid looking at bright screens 2-3 hours prior to bedtime
A study shows that two-hour exposure to light from self-luminous electronic displays led to suppression of melatonin by 22%.[8] This can already have a significant impact on one's ability to sleep.
2. Use blue light-blocking device
If you cannot avoid using blue light-emitting devices at night, then using a blue light-blocking device can be a good alternative. In one study, it shows that subjects wearing optical filter goggles produced almost the same melatonin as those exposed to dim light.[9]
3. Choose well your reading materials
Not all reading devices are created the same. When the team from Harvard Medical School compared the effects of paper books and light-emitting electronic readers on sleep, they found out that it takes longer to sleep with e-readers compared to paper books. The use of backlit e-readers can also lead to poor quality of sleep.
4. Spend time outside during daytime
Exposing yourself to light during daytime do not just boost your ability to sleep but also improves your mood and alertness during the day.
5. Try hypnotherapy
Guided hypnosis sessions from a licensed therapist can help you get better sleep. At Hypnosis in London, I offer hypnotherapy sessions for those who can't fall asleep due to various reasons, for those who keep waking up at night, and those who have insomnia.