“So we are abusing our circadian system by the misuse of light at night.”
The adverse impacts of inefficient artificial lighting
In November 2008, Verlyn Klinkenborg (in National Geographic) described how the human race has “invaded the night” with stray artificial light. Is it really ours to occupy? Vast numbers of the world’s species are nocturnal. The invasion of their world by our lighting has consequences that we are only just beginning to investigate and quantify. Wasted light and the trend towards bright, white ‘daylight’ exterior lamps are likely to have played their part in the disappearance of a large fraction of the world’s wildlife in the last 40 years:
Animals disturbed, and killed, as a result of stray light have no curtains to pull. There are many reports of its deleterious effects on large numbers of different species: distracted insects, migrating birds, disoriented fish, reptiles and mammals. Bats, moths, turtles, seabirds…. The list of reports of light disturbing their lives grows ever longer.
Professor Gerhard Eisenbeis, of the University of Mainz in Germany, has led considerable research into the impact of light spill upon insect populations, and speaks of a ‘vacuum-cleaner’ effect, sucking insects to their doom out of habitat areas. In an article in 2011 in the magazine Natur und Landschaft, entitled (in translation) Attraction of nocturnal insects to street lights, Professor Eisenbeis stated that
“Artificial lighting in the environment has had a deep impact on the natural world, especially on nocturnal animals. This takes place against a background of dramatically falling biodiversity in nearly all the Earth’s habitats. At the same time, artificial lighting is only one factor among many environmental pressures. Urban sprawl in the countryside, the conversion of natural habitats to intensive human exploitation and the release of artificial substances have contributed to a situation where biologists speak of the sixth wave of extinctions in the living environment.”
Nobody has said it better than Catherine Rich and Travis Longcore, authors of the definitive book (ISBN 978-1559631297) Ecological Consequences of Artificial Night Lighting:
“Nature needs the night”.
Surely humans are used to artificial lighting by now, aren’t they? The answer is no. Any species, from invertebrate to complex mammal, having evolved for millions of years to the rhythm of a day-night cycle, is not going to change its physiology in just 100 years to adjust to vastly more than the natural dose of light.
Not surprisingly, we find it difficult to cope with a life of international travel across time zones, working night shifts and sleeping in the day, staying up beyond dusk, staring at small, bright screens late into the evening, and living by the social clock rather than the solar one. Dr Steven Lockley of Harvard Medical School, who is a world authority on sleep disorders, writes:
“Access and exposure to artificial light at night have become pervasive in all industrialised nations and increasingly so in the developing world. This light affects all organisms exposed to it, not just humans, and the consequences of such a dramatic alteration in one of the most powerful environmental signals is not yet known. Given its relatively recent introduction, we are only at the beginning of understanding the impact of artificial light on human health. Research over the past 80 years, however, has shown that light exerts very powerful effects on human physiology, endocrinology and behaviour, and, having evolved in a distinct light-dark cycle, it is possible that unnatural exposure to artificial light at night is hazardous to human health”.
The hormone melatonin, a powerful antioxidant, scavenging free radicals and thereby helping to prevent cancer cell damage and proliferation, is secreted during the hours of darkness into the blood by the pineal gland in the brain – it is the biochemical signal of night. The efficiency of our immune system is partly regulated by melatonin. Melatonin levels are governed by the 24-hour circadian clock, which also controls the timing of many other bodily rhythms (e.g., the sleep-wake cycle, temperature, patterns of alertness, moods and performance). The circadian clock has an intrinsic rhythm close to, but not exactly, 24 hours and needs to be reset each day to synchronize with the outside world. The 24-hour light-dark cycle is the strongest environmental time cue to the clock, which in turn entrains its rhythmic outputs, including the melatonin rhythm.
Decreasing our exposure to light in the evening is therefore as important as receiving the right intensity of light during the day. Our bedrooms should be as dark as possible without compromising safety and measures should be taken to prevent exterior lights from shining into them. It is of course the obligation of the owner of the light to ensure this, not the victim of intrusive light.
A BBC report in 2003 confirmed that the vast majority of today’s children “have never experienced total darkness”, being surrounded all night, outside and indoors, with artificial lights. The report was quoting research sponsored by a power company, Powergen, which found that a startling 98% of British children do not sleep in darkness. In one in three households, a night-light remains on actually in the children’s bedrooms, at an estimated cost of £468 million a year. Powergen’s energy efficiency manager, Mike Newell, reportedly said:
“Coupled with the effects of street lighting, many of our children will grow up without ever knowing what true darkness really is.”
More and more research is being reported linking exposure to artificial light to human health problems. As a result, the American Medical Association (AMA) voted unanimously on June 16 2009 to support efforts to control light pollution, on the basis that, in their words:
- “Many species (including humans) need darkness to survive and thrive;
- Glare from bad lighting is a public-health hazard — especially the older you become. Glare-light scattering in the eye causes loss of contrast and leads to unsafe driving conditions, much like the glare on a dirty windshield from low-angle sunlight or the high beams from an oncoming car;
- Wasted light represents unnecessary energy and CO2 production”.
The AMA passed a resolution calling for:
- “All future outdoor lighting to be of energy-efficient designs to reduce waste of energy and protect the environment;
- Light-pollution reduction efforts and glare-reduction efforts at both national and state levels; and
- All future streetlights to be of a fully shielded or similar non-glare design to improve the safety of roadways for all, but especially vision-impaired and older drivers”.
The AMA encompasses the medical societies in all 50 U.S. states, and more than 120 specialist societies.
The British Independent newspaper reported in 2006 on research by Dr David Blask and colleagues (U.S. National Cancer Institute and National Institute of Environmental Health Sciences, Environmental Health Perspectives. Sept. 2007, 115(9): 1357-62), investigating why the incidence of breast cancer in rich countries is about five times greater than in developing nations. The study involved scientists grafting human breast cancer tumours onto rats, and then infusing them with blood taken from women during the day, in the early hours of the morning, and after being exposed to light at night. The ‘dark-night’ blood slowed the growth of the tumours by a reported 80 per cent; blood taken after exposure to the light had the opposite effect.
In 2008 a study at the University of Haifa, Israel, by chronobiologist Professor Avraham Haim, doctoral student Itai Kloog, and Professor Boris Portnov concluded that exposure to light at night may be a significant cause of breast cancer. Breast cancer is the second most common type of cancer in the USA, and the most common in the UK, and in Israel. The Israeli researchers stated that women in street-lit towns are “37 per cent more likely to suffer from the disease than others in dark areas, and (the risk is) a further 27 per cent higher in areas with the highest amount of outdoor lighting” (Chronobiology International 2008, and 2011 Feb. 2011, Vol. 28, No. 1). The work was described to delegates at the Eighth European Dark-Sky Symposium in Vienna (2008) by Itai Kloog, who related how NASA satellite images had been used to compare light emitted from various towns and villages throughout Israel with breast cancer statistics from the Israeli National Cancer Registry. The researchers also investigated as controls many other factors (socioeconomic, environmental, and genetic) of the women’s lives. “We are not saying that light at night is the only, or even a major factor in breast cancer,” said Kloog. “However, the strong correlation is there. It must be taken into account.”
Studies elsewhere, by other researchers, of night-shift workers (for example, nurses and flight attendants) have found rates of breast cancer considerably higher than normal. Interestingly, rates of breast cancer in totally blind women have been found to be less than average.
Professor Charles Czeisler of the Harvard Medical School commented in 2006:
“If light were a drug, the government would not approve it.”
Professor George Brainard, director of the Light Research Program at Philadelphia’s Jefferson Medical College, said, also in 2006:
“Humans evolved on a planet without electric light over thousands and thousands of generations. The body is designed to be alert and awake during daytime hours and to sleep at night. Now we have a 24/7 society that isn’t in harmony with our biological design.”
So the doctors and academics, echoing the dark-sky campaigners, stress that we tamper with our age-old day/night responses at our peril.
Evidence piles up that the indiscriminate use of light is not as harmless as was once thought. When we finally get lighting right, it will be good not only for our view of the stars above, but also for the very fibres of our being.
Further research is required to understand fully the impacts of artificial light on all classes of living things and the environment as a whole. The precautionary principle applies: enough is known about the ‘dark side of light’ to take action now.
We have evolved with the consistently predictable, daily rising and setting of the sun. It’s something our biology have taken for granted for millennia.
On average 12 hours of light followed by 12 hours of dark with seasonal variations with increase distance from the equator.
Our biology has evolved to function best with bright days and dark nights and consistent light/dark cycles. Our bodies have evolved to use natural light and dark to tell the time of day, month, and season and to adjust our behaviour and physiology accordingly.
At night the only light our ancestors saw, was that of the moon, the stars and more recently firelight. They would have seen a 100,000 fold difference between light and dark (sunlight to moonlight). Today many people may only see a 100 fold difference between light and dark, due to days spent indoors and the use of artificial light at night. Industrialisation moved people from spending most of their day outside working on the land to spending most of their time inside dimly lit buildings. But it wasn’t until this century that exposure light at after dark became ubiquitous and normal for most people in industrialised countries.
Every cell in our body has an internal clock that keeps us in-sync with our spinning planet. We have a central clock in the SCN in the brain which is reset by light and which keeps all the other clocks in sync.
At dawn our eyes receive sunlight which resets (entrains) the central clock in the brain. Around 12 hours later our pineal gland, located in the middle of our head, begins its nightly secretion of Melatonin into the blood stream. Artificial light at night suppresses this melatonin flow. The brain perceives the blue light hues of the artificial light as day and so does not start it nightly secretion until the lights are switched off.
Melatonin is well known as a sleep hormone, it is also the most potent antioxidant and a multi-functioning anti-cancer agent. Once it is dark, the levels of Melatonin in the blood rise slowly at first then accelerate up until about 3 am when they peak and then begin to fall back down to low daytime levels. These nightly levels have been shown to have very powerful antioxidant and anti-cancer effects.
Along with melatonin the pineal gland also secretes other anti-cancer agents. As a result rather than taking melatonin it may be better to maximise your natural pineal gland output as it includes these other pineal extracts. Taking melatonin may have adverse effects on your bodies own production.
Our nights began being illuminated in a significant way with gaslight in the early 1800s and then the invention of the electric bulb by Thomas Edison which became common place in the early 1900s. Brighter and whiter artificial lighting now pervades the modern world after dark. Our brains see this artificial light as ‘day’ and the nightly secretion of Melatonin is delayed until the lights go out.
Our daily up down rhythm is of Melatonin is suppressed as our ‘dark’ nights are now shorter, brighter, irregular and disrupted.
SHORTER: Shorter nights mean our duration of melatonin is reduced from the optimum 11-12 hours.
BRIGHTER: Nights are often illuminated, from street lighting coming in from outside, or from lights left on all night long, this further suppresses melatonin.
IRREGULAR: The sunset our ancestors would have experienced would have been at almost the same time everyday, with steadfast regularity. In our modern world our sunset is when we switch off the lights and screens of the tv, computers and phones. The timing of which can vary greatly from day to day. This disrupts our biological clock, and weakens our rhythms.
DISRUPTED: If we do sleep in the dark, our dark night may be interrupted by looking at the screen of our phone to check the time, or turning a light on to go to the toilet, during the night. This tells our biological clock that it is dawn and stops the production of melatonin.
In 2002 scientists discovered that it is predominantly the blue light wavelength, that our brain recognises as ‘day’. Special blue light receptors in our eyes send the messages to the master clock telling the brain that it is day and the master clock tells the pineal not to secrete melatonin. White light contains a high proportion of blue light, especially ‘colder’ white light. The cold light of modern energy saving light bulbs and LEDs emit far more blue light than their predecessors. Computer screens, televisions, tablets and smart phones all emit a large amount of blue light wavelengths.
This was an important discovery because it means that if we remove this blue light from our evenings we can regain our optimal 12 hours of melatonin without having to switch everything off and stumble around in the dark. Studies have shown that after removing this stimulating blue wavelength, people found it easier to fall asleep, they had a deeper nights sleep and felt more rested in the morning.
Melatonins anti-cancer effects
Every cell in the body, including cancer cells have receptors for melatonin. It literally tells our cells that it is night time, and time to rest.
Melatonin is powerful antioxidant and helps activate the immune system. It prevents cell mobility that causes cancer to spread and prevents the growth of blood vessels that provide nourishment for cancer cells. Melatonin blocks oestrogen’s cancer stimulating effects and the ability of tumours ability to stimulate localised production of oestrogen. It interferes with the cancer cell cycle leading to cancer cell death and blocks Telomerase’s ability to make cancer cells immortal. Melatonin promotes normal daily rhythms which helps prevent cancer and prevents the cancer promoting action of certain genes. It accelerates the process by which immature cells become differentiated mature cells- preventing cancer. Melatonin alters fat metabolism and interferes with the ability of many tumours to use the fatty acid linoleic acid as a growth signal, this causes tumour metabolism and growth to be shut down. Melatonin has been shown to greatly enhance the effectiveness of tamoxifen a drug used to treat breast cancer.
All of these actions mean that our bodies own Melatonin and other pineal agents can have a huge impact on both the prevention and treatment of cancer.
Animal and human studies
A study of turkeys showed ovarian cancer tumours shrink and in some cases disappear completely in long nights- 8 hours of light and 16 hours of dark (L:D 8:16) conversely it was found that tumours grew larger in the turkeys that were subject to 16 hours of light and 8 hours of dark (L:D 16:8).
In 2005 Scientist Blask, Brainard and others took blood from human female volunteers under three conditions; 1) during the day, 2) at night and 3) at night after light exposure. The blood from the three conditions was then supplied to rats that had human breast cancer tumours grafted on to their backs. They found that the tumours did not grow or grew very little with the melatonin rich night blood. They found that the tumours grew rapidly when exposed to the day blood, and ‘night with light exposure’ blood, both of which contained no melatonin.
Very low levels of light (0.2 lux) eg light leaking under a door can increase rates of tumour growth in rats (Dauchy RT et al. 1997).
Human studies have shown;
Significantly higher cancer risk in shift-workers, particularly rotating night shiftworkers, who have minimal night time levels of melatonin.
A 30% lower cancer risk in totally blind people, who have melatonin all the time.
Epidemiological studies have shown that cancer is 5 times more prevalent in industrialised societies compared to non-industrial societies.
One study by Verkasalo showed women who consistently sleep 9 hours or more have ¼ rate of breast cancer of women who sleep 7 hours of less.
A study of outdoor artificial lighting at night and breast cancer incidence in Israel found that women living in neighborhoods where it was bright enough to read a book outside at midnight had a 73% higher risk of developing breast cancer than those residing in areas with the least outdoor artificial lighting.
There are easy steps to increase your body’s nightly melatonin production, returning it to the ‘normal’ levels in which we have evolved, in order to protect your health. Getting daylight in the day, going amber in the evening, and sleeping in dark, much like we have evolved being outside during the day, having firelight in the evening and sleeping in the dark.
It is important to get a minimum of 30 mins outside each day. This can be 10 mins in morning, 10 mins, at lunch and 10 mins in the afternoon. This entrains your master body clock (SCN) and helps increase melatonin levels at night.
You can remove bluelight wavelengths in the evening by protecting your eyes with amber glasses and or removing the blue light from the light source.
Adjust your evening lighting to yellow or amber. Yellow or amber energy saving bulbs on amazon
Install blue-blocking apps on electronic devices eg f.lux on computers twilight on smart phones, or use yellow film screen protectors electronic devices.
Turn the contrast and brightness down on your television and cover with yellow film.
In situations where lighting cannot be changed- blue blocking glasses can be worn eg when out at night, at a friends house or in hospital. There are regular blue-blocking glasses and fit-over glasses, which you can wear over normal glasses.
When you go to bed, you need to sleep in total darkness.
If you find you often fall asleep with the light on, you could use one of these Ansmann plug sockets which turns off automatically after 15mins, 30 mins, 1 hour, 2 hours etc. Or plugs that you can switch off with a remote control
If there is light coming in from the street, use thick curtains or a black-out blind or sleep with an eye mask on if its easier.
If you need to turn on a light to go to the toilet at night make sure it dim and yellow, amber or red.
Pineal gland is susceptible to damage by high levels of fluoride via the displacement of iodine, which can reduce your melatonin production. If you live in an area with fluoridated water you can reduce your fluoride consumption by only drinking filtered or bottled water. You can ask your GP for an iodine deficiency test and you can increase iodine naturally by taking sea kelp or eating eggs, fish and sea vegetables.
Here is some more info about it http://articles.mercola.com/sites/articles/archive/2013/06/29/iodine-deficiency-risk.aspx
It is not just sleep and cancer that our effected by reduced sleep and reduced melatonin. Optimising natural melatonin can help a variety of conditions, or put another way a lack of melatonin may show itself in variety of conditions depending on a persons genetic dispostion and other environmental factors.
Other diseases/medical conditions which are reported to be affected by reduced sleep and or reduced melatonin production include; obesity, diabetes, heart disease, autism, altzeimers, parkinsons, depression, bipolar, schizophrenia, auto-immune diseases, migraines.