Recent research has shown that reading from tablet, phone or laptop before bed not only makes it harder to fall asleep, but may actually even reduce your level of alertness the next day. Poor sleep can contribute to the causation of cancer, diabetes, heart disease, and obesity.
Light plays a very vital role in human health as it influences hormone secretion, heart rate, alertness, sleep propensity, body temperature, and gene expression. The advent of devices with screens, especially the energy saving lighting design is increasing the exposure of human eye to light in particular the harmful blue wavelength even after sunset.
What is peculiar about blue??
We are surrounded by Blue light which is said to be subtle and dramatic. The perception of light includes glare and brightness which are functions of wavelength. The short wavelength of blue light makes it the most energy efficient light for humans as it is perceived as the brightest.
Advantages of blue light
Several studies have shown beneficial effects of blue light in day time –
- It is superior to other wavelengths in enhancing responses in the left frontal and parietal cortices during a working memory task
- It leads to quicker auditory reaction times and fewer lapses of attention compared to green
- Blue wavelengths suppress sleep-associated delta brainwaves and boost the alpha wavelengths, which are related to alertness
- Blue light is more powerful in elevating body temperature and heart rate and in reducing sleepiness compared to green light
As the natural light from the sun fades away, our body systems also slow down and natural body clock gradually begins to prepare us for the ‘Sleep mode’. This means our alertness and attention slowly declines which is a prerequisite to sound sleep. In such situation, the features that serve as an advantage to the use of blue light in daytime are the cause for its detriment after sunset.
Disadvantages of blue wavelengths at night
Suppression of melatonin:
Darkness signals the release of melatonin and its levels begin to rise sharply after 9pm and slowly our alertness declines. Melatonin is active for up to 12 hours i.e. till 9 am and falls to very low levels which are not noticeable enough to produce an effect in daytime.
The blue wavelength suppresses melatonin for about twice as long as the green thereby increasing alertness and reducing sleep.
Disruption of circadian rhythm :
The body has its own biological clock called the internal circadian rhythm which regulates the timing of periods of sleepiness and wakefulness throughout the day. The circadian rhythm dips and rises at different times of the day, so strongest sleep drive in adults is between 2:00-4:00 am and in the afternoon between 1:00-3:00 pm. Depending on whether an individual has had sufficient sleep, the sleepiness felt may be more or less intense.
Blue light shifts circadian rhythms by twice as much (3 hours vs. 1.5 hours) as green light.
Blue or no blue ?
Now, we can see that blue wavelengths have benefits and drawbacks depending on the timing.It is prudent to get the blue wavelength to work in sync with the cicadian rhtyhm. Increasing blue portion of artificial light in daytime may improve performance and learning ability in school kids and employees working indoors, and health will be improved in patients staying at nursing homes or hospitals. Minimizing exposure to blue wavelengths at night-time protect shift workers against disorders such as cancer and cardiovascular disorders as well as reduce sleep disturbances and their consequences among the general population
Solution to get rid of the blues
If we feel that our work or lifestyle makes it inevitable to use the laptop, tablet, phone just before bed then there is a way to make its use less harmful. Certain apps on phones (Android), or physical filters (for iOS) or softwares for laptops/computers (F.lux) can help to block the blue light.
Nothing can replace a good quality sleep. Sleep is by far the most underrated component of health often taken for granted unless we experience severe insomnia. We are well aware of the multiple harmful effects of mobile phones, tablets and laptops on health and well being. Here is one more reason to restrict use of these smart gadgets. As the technology is getting smart(er), we need to find ways to out-smart technology!