01 Dec Light Pollution?
We’ve all heard of the effects of air pollution and water and land pollution. If you live near an airport or have teenagers, you’ve likely experienced the effects of noise pollution. But few of us have heard of light pollution. A few days ago, I was awakened by my infant daughter at an hour when most people are still dreaming. I noticed the glow of street lights seeping in through my blinds. As I embark on a project to sew black-out blinds for my bedroom, I thought I would review (for myself) and you, the effects of light pollution on our health.
Our “Internal Clock”:
All living beings operate under the influence of a circadian rhythm; a daily “internal clock” which runs on a (approximately) 24 hour cycle. Circadian rhythms determine sleeping/waking and feeding patterns in all animals (including humans). Body temperature, brain wave activity, hormone production, cell regeneration and many other biological activities are linked to this daily cycle. In mammals, the internal “master clock” is located in the suprachiasmatic nucleus (SCN) located in the hypothalamus (a part of the brain).
Melatonin is one of the primary hormones affected by the circadian rhythm. The pineal gland, in response to signals from the SCN, times the release of melatonin at night with peak secretion occurring between 1am and 3am. Melatonin secretion also provides feedback to the “master clock”; helping it to calibrate its rhythm. Melatonin is a hormone which is extremely important to our health.
Light and the Biological Clock:
Although our biological daily rhythm will run in the absence of external changes, the primary cue which humans use to calibrate our biological clock in light as it is perceived by special receptors our eyes. Exposure to light decreases melatonin secretion and can advance or delay our circadian rhythm.
Particularly affected are shift workers who are exposed to light during night time hours and people living in the extreme North where the sun is above the horizon throughout the summer months. Flight attendants and pilots who travel across time zones experience regular disruptions in their circadian rhythms. Exposure to light and electromagnetic radiation (from living near power lines and from appliances such as clock radios, televisions, electric blankets, etc. within 2.5 feet of us while we sleep) which disrupt our biorhythms, and particularly the circadian secretion of melatonin can have serious health effects as outlined below.
– Melatonin secretion declines naturally with age, making sleep disorders more common in the elderly.
– At puberty, circadian rhythm cycles also undergo change. This explains increased daytime sleepiness and night time waking which is so common in teens.
– Jet lag result is insomnia, fatigue, and disorientation.
– Delayed Sleep Phase Syndrome: people with DSPS tend to persistently fall asleep very late and have difficulty waking in the morning.
– Advanced Sleep Phase Syndrome: a disorder in which evening sleepiness, early sleep onset (between 6 and 9pm), and earlier waking than desired (between 3 and 5am) occur. This occurs especially in the elderly and those with depression.
– Irregular sleep-wake schedule: in these patients, sleep/wake cycles and other daytime activities (such as eating) are irregular and do no correlate from day to day. This is seen more often in people with neurological impairments and dementia.”
– Treatment of sleep disorders with timed melatonin supplementation is safe, effective, and relatively inexpensive.
– Melatonin is an extremely important antioxidant in the body and, since it is both fat and water soluble and can pass through every blood barrier in the body, it can protect all parts of the human cell in every part of the body from oxidative damage. It is also important in stimulating the immune system which is also helpful in preventing tumor growth.
– Cancer growths occur more often in mice exposed to permanent light. Mice suffering from cancer die more often under the influence of light pollution than mice who have undisturbed day/night cycles.
– Disruptions in melatonin synthesis have been linked to increased risk of breast, large intestine, and rectal cancers in humans.
– Cancer patients have melatonin levels that are 30-40% lower than people who are cancer free. Aggressive tumors tend to cause a further decline in melatonin.
– Breast cancer rates increase dramatically in women who work the night shift.
– Interestingly, blind women have 20-50% lower rate of breast cancer.
– Melatonin is used as a treatment for several cancers and has shown to improve survival time and quality of life and may even cause regression of some cancers.
Other Health Effects:
– Gastrointestinal disease is linked with suppressed melatonin production. Shift workers tend to report a higher incidence of GI symptoms.
– Cardiovascular disease also increases (by up to 40%) in shift workers. Patients with coronary heart disease tend to have lower levels of melatonin. Melatonin positively affects good to bad cholesterol ratios and decreases platelet clumping which also decreases the risk of cardiovascular disease.
– Changes in biorhythms also affect mood. Disordered melatonin production may play a role in Seasonal Affective Disorder, Depression, and Bipolar Disorder.
– Many medications affect melatonin secretion. Among them are antidepressants and beta-blockers.
– Interestingly, it has been found that timing certain medications in coordination with our circadian rhythm increases efficacy and decreases side effects.
Light pollution affects animals as well as humans. For more information, see the website of the International Dark-Sky Association at www.darksky.org
It is very important to sleep in complete darkness. If you live in an area where street lights abound, use blackout shades. Use motion-sensitive night lights so that your children are not exposed to continuous light at night. Turn off all electronic equipment when you go to sleep. Try to get light exposure during the day, especially in the morning. Exercise, particularly outdoors and early in the day, to help regulate melatonin production. Maintaining a regular schedule is also helpful in regulating our circadian rhythm. If you are a shift worker or travel across time zones frequently, you may need extra help maintaining your melatonin levels.
As one of my daughters’ favorite books (Pajama Time by Sandra Boynton) says: “Hop into bed, turn out the lights, you can have a party in your dreams tonight!
Please Note: This information is for educational purposes only. Consultation with a licensed health care practitioner is recommended for anyone suffering from a health ailment.
If you have any questions, or would like to schedule an appointment, please feel free to contact Dr. Leat Kuzniar, ND at 201-757-5558 or, through email at firstname.lastname@example.org.