Author : Dr. P. D. GUPTA
Former Director Grade Scientist, Centre for Cellular and Molecular Biology, Hyderabad, India
www.daylife.page
Light energy is the only form of energy exists in two forms (a) particle and (b) waves. Nearly everything we know about the universe is because of light. Particles of light, called photons. The distance between peaks from one wave of light to another is called the wavelength–shorter wavelengths mean the photon is more energetic, while longer wavelengths indicate lower energy. Humans perceive differences in wavelengths as color; this was shown by Sir C V Raman who got Nobel Prize in Physics. Invisible gamma rays and x-rays have the shortest wavelengths, and microwaves and radio waves have longer wavelengths. Light quality has different effects on us. For example,
· Natural light: Light that mimics the sun is best for your health.
· Blue light: Blue light can suppress melatonin production more than other colors of light. Cool white light:
· Cool white light can make us healthy, fresh and full of energy and help us to concentrate
Light can affect our body in many ways, for example:
Sleep: Disturbed sleep by interfere in melatonin production: Light suppresses melatonin production, which can disrupt your sleep cycle. Light exposure at night and eye strain can also disrupt our sleep and cause headaches
Mood change: Light stimulates serotonin production, which can improve our mood and cortisol levels: Reduced light exposure can cause fluctuations in cortisol levels, which makes us feel drowsy.
Perception: Light can impact your perceptions, emotions, and overall well-being.
Health Weight: Light supports metabolism and can help us maintain a healthy weight.
Heart disease, diabetes, and cancer: Exposure to artificial light at night can increase our risk of these diseases
Light at night and cancer
The World Health Organization listed ‘light at night’ as a possible carcinogen in 2007. From streetlights and outdoor accent lights to the glow of TVs, lamps, and cell phones… artificial light at night is ubiquitous. Let me give you the background science on the biological pathway through which light at night impacts cancer risk.
We plan an innovative experiment to prove that light at night increase the chances of developing cancer. For more details one can refer the book” Dark Dark Side of the Night Light”. The disturbance of circadian rhythm and production of melatonin due to exposure of artificial light during night time affects our endocrine system. Our pilot epidemiological survey provided evidence practically no breast cancer develops in blind women, gave a clue for the consequence of over exploitation of light in the modern civilization disturbing natural circadian rhythm and reduced production of anti- cancer hormone “Melatonin”. Artificial light may be one of the strong risk factors for the development of breast cancer.
Melatonin and cancer prevention:
Melatonin, which most people think of as ‘the sleep hormone’, rises at night and falls during the daytime. Maintained in almost all animals, this is a circadian rhythm governed by the light hitting the retina of the eye.
Melatonin, though, is not just a sleep hormone. In addition to circadian signaling, recent research shows that melatonin acts as an antioxidant within cells, helping to combat oxidative stress in our cells at night. While we sleep, our cells go into rest and repair mode, cleaning up the waste from the active period during the day. When cells are exposed to too much oxidative stress, it can lead to DNA damage.
There are two factors governing melatonin production overnight
· Exposure to light during the day
· Absence of light at night.
First, let’s look at light exposure during the day:
Melatonin levels are affected by the amount of light (specifically in the blue wavelengths) that you get during the daytime. An animal study showed that increasing blue wavelengths (465-485) during the day caused a 7-fold increase in nighttime melatonin levels compared to animals kept under standard fluorescent lighting. The animals exposed to blue-enriched light during the day also had markedly reduced tumor growth. The increased melatonin production leads to a decrease in the Warburg Effect, which is the shift to glycolytic metabolisms that cancer cells exhibit.
Other studies have shown similar results – increased melatonin causing decreased tumors. The second factor impacting overnight melatonin production is exposure to light at night:
The rise in melatonin at night is governed by the decreasing amount of blue light hitting our eyes in the evening hours. Researchers refer to this rise in melatonin in the evening as ‘dim light melatonin onset’. While suppressing melatonin with lots of blue light during the day is good, the opposite needs to occur after the sun sets. At night, we need melatonin levels to rise as much as possible. Studies over the last twenty-plus years have made it clear that light at night (dim or bright) causes a decrease in melatonin levels.
Safe light
Make sure that the bulbs you are choosing are compliant with the standards of photobiological safety. The risk-free group means that there is no photobiological hazard. Risk Group 1 means that there is no photobiological hazard under normal conditions of use. Risk Group 2 means that there is no photobiological hazard associated with the reaction of the eye to bright sources of light. The final risk group, Group 3, means that photobiological hazard occurs even during a short exposure, and the bulb should not be used.
What are the hazards associated with the use of light sources that are not compliant with the standards?
● Hazard to the eye and skin from actinic UV radiation.
● Hazard to the eye from UV-A radiation.
● Hazard to the eye from blue light.
● Hazard to the eye from infrared (IR).
● Thermal risk to the skin.
● Thermal risk to the retina.
Even though photobiological safety is one of the basic requirements included in European directives, many marketed light sources do not comply with these standards. Make sure that you are using bulbs and lamps from renowned manufacturers, with certificates of marketing authorization. However it is better to switch off lights and sleep in dark if one wants to reduce the chances of developing hormone dependent cancers.
