Our house, including the bedroom is full of lights from computer monitors, clock radios, blinking and glimmering electronic devices. But, chronic exposure to light at night causes health problems.
Long time ago, people were exposed to different kinds of natural light responsible for controlling circadian rhythmicity. People had sunlight during the day, while at night there were the stars and the moon, and maybe the light from campfire.
In the modern world we live today, we have artificial lighting at night.
The difference between sunlight and moonlight induces critical biochemical flow series tied to light periodicity, including the creation of cortisol and melatonin levels.
How melatonin functions?
Melatonin is produced by the brain at night in order to regulate our cycle of sleeping and waking. Melatonin decreases blood pressure, glucose levels, and body temperature, which are the most important physiological responses in charge for restful sleep.
The optic nerves in our eyes senses light and sends a signal to the brain that it’s time to wake up. It also increases body temperature and produces hormones like cortisol. The levels of cortisol are low at night and thus allow us to sleep. The cortisol levels are higher during the day and allow us to stabilize the energy levels and the modulation of immune function.
If your rooms are dark at night, the optic nerves in your eyes won’t send a signal to the brain and your body would be able to create the needed melatonin. The levels of melatonin are controlled according to the amount of light exposure during the previous day.
The Light before Going to Bed
Studies have proved that the melatonin duration can be shortened by about 90 minutes because of exposure to room light before bedtime compared to dim light exposure.
Indeed, studies have shown that exposure to room light before bedtime shortens melatonin duration by about 90 minutes compared to dim light exposure. Additionally, exposure to room light during usual hours of sleep restrains the levels of melatonin by more than 50%.
Many of the modern devices we have emit blue light from light-emitting diodes. This light is particularly effective at suppressing melatonin. This happens because the photopigment melanopsin, which is found in specialized cells of the retina involved in the regulation of circadian rhythms is most sensitive to blue light.
Moreover, scientists inform students about the impact of light from computer monitors on the levels of melatonin. The computer light at night, especially blue light lowers the melatonin levels in students. Another study found that backlit tablet displays restrain melatonin and disrupts sleep. Remember that the usage of self-luminous electronic devices before going to bed may interrupt sleep even if melatonin is not repressed.
Melatonin and Cancer
It is not strange that this hormone and biochemical disturbance can create negative effects, including cancer.
A study that lasted for 10 years and in which participated over 1670 women, showed that those women exposed to higher intensity light in their sleeping environment had higher risks by 22% of developing breast cancer by melatonin repression.
Low Light, Blue Light, Depression and Their Effect on the Immune System
The light at night doesn’t even have to be bright in order to cause problems. Frequent exposure to dim light at night can cause depression-like symptom in hamsters. But by returning the hamsters to a normal, non-lit day/night schedule, the researchers succeeded in reversing the depression. Scientists think that this dim-light depression is caused by a protein called tumor necrosis factor.
Moreover, the immune system can be affected by the chronic dim light at night.
Premature Aging and Heart Problems
Because the hormone melatonin has antioxidant properties too, it plays an important role in anti-aging. Scientists succeeded in treating artificially aged mice with melatonin, thus reducing oxidative stress.
Light at night also affects weight gain by changing the time of our food intake. When exposed to LAN, mice gained more weight, besides exercising and eating as much as the mice exposed to darkness. Another thing that scientists linked with low melatonin levels is diabetes. However, it is not clear what role LAN plays in this matter.
Keep your bedrooms as dark as possible and avoid blue light before going to bed. It is advisable to turn off all your gadgets that are emitting light and close the blinds. Also, if possible, avoid using your tablet, computer or smartphone in the hours before sleep.