Circadian rhythm controls a remarkable number of metabolic and physiological functions, including DNA expression. New evidence shows a strong link between the human molecular clock and whole-body homeostasis – i.e. the body’s ability to achieve general balance and equilibrium.
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The word circadian comes from the Latin circa diem, meaning “about a day” or more literally “around a day.” The Earth’s 24-hour rotations affect you far more than you may realize – your eating and sleep-wake schedules, hormone production, organ function, brain wave activity, body temperature, and cell regeneration.
To put it bluntly, your body’s cells can’t tell what the hell is going on if you don’t sleep and wake on a regular schedule.
Just as certain work tasks are best done at certain times of day, so your organ and hormonal functions are designed to take place at specific times for optimal performance.
Before electricity, people went to bed shortly after sunset and arose at sunrise. You could barely mange to read or play a game of cards by the light of a fireplace or candle.
With the dawn of electricity, our circadian clocks can be synchronized to external cues that we control, but the results are not very healthy.
Major consequences of our modern lifestyle include circadian rhythm disruption, sleep disturbances, mood swings, brain fog, depression, and chronic disease.
Mounting evidence shows that altered circadian rhythms are also linked to increased cancer risk.
Does sleep deprivation cause cancer?
Three main sleep issues are linked to cancer – sleep deprivation, sleep apnea, and shift work sleep disorder.
Chronic Sleep Deprivation
Even one night of insufficient sleep can result in brain fog, poor judgment, a weakened immune system, weight gain, and the inability to remember or concentrate.
But chronic sleep deprivation – regularly getting less than seven hours, night after night – is linked to increased cancer risk:
- Prostate cancer – men with insomnia are twice as likely to develop prostate cancer, according to a study that followed 2,000 men over five years.1
- Colorectal cancer – people averaging less than six hours of sleep have a 50% higher risk of colorectal cancer.2
- Breast cancer – postmenopausal women who sleep fewer hours suffer more aggressive forms of breast cancer than do those who sleep longer.3
Usually occurring side by side with obesity, diabetes, and heart disease… recent research also links sleep apnea to cancer.
- Head and neck cancer – four out of five head and neck cancer patients have sleep apnea.4 (I don’t know about you, but I thought this fact was astounding.)
- Overall risk – people with severe sleep apnea have a 65% greater risk of cancer.5 Those with severe sleep apnea are five times more likely to die from cancer than those without it.6 Fragmented sleep due to sleep apnea accelerates cancer growth in mice.7
Both jet lag and shift work – especially night or rotating shifts – disrupt your circadian rhythms. You’re awake when your body needs sleep.
Studies show that shift work is linked to cancer. In 2007, the International Agency for Research on Cancer (IARC) even classified shift work as probably carcinogenic.8
Twelve epidemiological studies have investigated the link between shift work and breast cancer. Eight reported a positive correlation, the other four did not. Inconclusive, but it is telling.
Any nighttime exposure to light suppresses nocturnal melatonin and its anti-carcinogenic benefits.
According to additional studies:
- Decreased melatonin levels link to higher breast cancer risk – possibly because melatonin helps control estrogen.9
- Higher melatonin levels are correlated with fewer and smaller breast cancer tumors.10
Also, cortisol levels should peak at dawn; but for shift workers they peak early in the afternoon… which may also pose an increased cancer risk.
A word about melatonin and cortisol is in order here. Our bodies gradually build up melatonin during the day, while cortisol levels fall. At night before bedtime, our melatonin levels are at their peak, telling us to go to sleep.
Cortisol is the opposite. It builds up during the night and peaks in the morning, telling us to wake up and start doing stuff. It’s the stress hormone, released when we’re worried, frightened or anxious. This is why people suffering from chronic stress often have insomnia. But in normal, healthy amounts, cortisol is a good thing and gives us energy.
Both melatonin and cortisol respond to light. That’s why our ability to produce light in the middle of the night – unknown to our ancestors – has disrupted our levels of these two hormones.
The dark side of the ‘brightest’ invention in history
Could the much-hailed invention of the light bulb be a curse in disguise?
In 1987, Richard Stevens first proposed that electric lighting (LAN, or “light at night”) could promote breast cancer.11 His theory was that LAN disrupted melatonin production and the circadian cycle.
A 2008 study used NASA photos to estimate LAN levels in 147 Israeli communities. They found a strong positive correlation between LAN intensity and breast cancer rates – a stunning 73% higher breast cancer rate in the highest LAN areas versus the lowest LAN areas.12
Three subsequent studies confirmed this… the most recent one a 2016 Connecticut study.13
Incidentally, prostate cancer also appears to be strongly linked to LAN.14
Want to see the LAN intensity in your area? Here’s a telling map:https://cires.colorado.edu/Artificial-light.
It’s common knowledge that caffeine can mess with your circadian clock.15 A double espresso’s 200 mg of caffeine three hours before bedtime causes a 40-minute delay in your internal clock’s signal that it’s time for bed. (And the delay can be much longer than that for some indiviudals.)
But there’s an interesting part of the study the press totally ignored. . .
Bright light is a far worse culprit than caffeine. It singlehandedly triggers circadian delays of 85 minutes – double that of the double espresso!
Compared with dim light, brighter lights before bedtime suppressed melatonin onset in 99% of individuals – effectively everybody — and shortened the length of the melatonin part of their daily cycle by 90 minutes, on average.16 So if you think bright lights don’t affect you, dream on (assuming you’re able to get to sleep. . .)
The confounding role of age
Age is another important factor in our “talent for sleep.” As you advance in years, you lose your ability to sleep soundly. By age 64, nearly half of us suffer from a sleeping disorder.17
It seems your response to external light cues worsens as you age. Older people tend to sleep less and wake up more during the night. Besides light, the need to urinate frequently is often a cause. Get it fixed, whatever it takes. Pain is another reason for poor sleep. These medical problems are treatable – and usually with a natural solution – but you have to be determined and keep searching.
And don’t think you’re off the hook just because you’re younger. Researchers found that both the quality and duration of sleep plummet dramatically between ages 20 and 59, often by the age of 30.18
You might also be interested to know that research links a healthy biological clock to a longer life.19
Given all this, the message is clear: make quality sleep a priority.
Your circadian rhythm controller
A tiny organ called the suprachaiasmatic nucleus (SCN) located at the base of your hippocampus is the master control center for your circadian cycles. It synchronizes light signals that regulate your sleep hormone, melatonin. At dusk, SCN signals melatonin to get ready for sleep.
But this signaling mechanism is highly sensitive to disruption and its timing can easily be thrown off. If you’re burning the midnight oil, you’re not doing your brain or your health any favors.
The time to take action is today.
10 tips for better sleep starting today
Start with these sleep hygiene basics. If they don’t get the job done, consider the supplements in the next section. But if you don’t try these first, don’t expect supplements to be a miracle cure for your sleep problems.
The most critical phase of sleep is non-REM slow wave sleep (SWS), or deep sleep – when your body regenerates tissue, builds bone and muscle, and detoxifies and rejuvenates your brain and organs.
This restorative deep sleep occurs early in the sleep cycle, so it’s important to prioritize good sleep preparation.
As a side note, please skip prescription pills, which come with a host of side effects, are addictive, cause sleepiness the next day, work poorly… and are linked to cancer.
1. Stick to a set sleep schedule seven days a week, even on weekends. This means, don’t sleep late on weekends. Get up at your usual time.
2. Shut down the kitchen and turn down lights and phone/tablet/computer screens 90 minutes before bedtime. Screens emit a great deal of light in the blue end of the spectrum, like the sun. This increases cortisol (stress) and leads to disrupted sleep. You shouldn’t be looking at the ‘sun’ at 9, 10, or 11 pm. It’s devastating to your circadian rhythm.
One idea is to wear blue-blocking glasses in the evening to remind your body it’s not noon. Install https://justgetflux.com/ on your computer… it’s free and automatically blocks blue light from dusk to dawn.
3. Get outside first thing in the morning to train your internal clock to follow the sun. Expose your skin to the sun (without burning, of course). Skip the sunglasses. A handy comparison of sun to indoor lights: moonlight is about 1 lux… a brightly lit office 400 lux… a cloudy day 2,000 lux… a sunny spring day 40,000 to 60,000 lux… and bright summer day about 120,000 lux. Can you see why getting outside is so critical in distinguishing night from day?
4. Exercise daily, preferably early in the day.
5. Start a gratitude journal. Helps reduce stress. If you’re serious about boosting your deep sleep, you must also get serious about slashing stress.
6. Cool your room. Studies show that optimal sleep temperature is 60-68F (15.5-20C).
7. Sleep in a pitch-black room. Consider installing blackout shades, and unplug all light-emitting gadgets, chargers, and clocks in your room. Or wear a blackout eye mask. It should be dark enough that you can’t see your hand in front of your face. Cover those little lights that are on practically every device, to tell you it’s plugged in. Who needs to know that?
8. Avoid caffeine after noon and wine in the evenings. Oddly enough, alcohol is a sleep disrupter.
9. Strive to be in bed by 10:30 at the latest.
10. Cut your exposure to EMFs by shutting off your cell phone, removing TVs and other devices from your bedroom, and turning off Wi-Fi at night (you’re sleeping anyway, so you won’t notice). Significant evidence points to EMFs as a sleep disruptor.
Nutrients for an extra boost
If the steps above aren’t enough, these vitamins and herbs are known to help promote sleep:
- 5-HTP – helps replenish serotonin, which in turn produces melatonin.
- GABA (gamma butyric acid) – calms your nerves. A small UCLA study showed that it increased total sleeping time by 73% compared to a placebo.20
- Combined 5-HTP and GABA – improved duration and quality of sleep better than either of them separately.21
- L-Theanine – increases alpha wave activity in deep sleep. Boosts dopamine, serotonin, and GABA production.
- Vitamin B-6 – deficiency is linked to insomnia and sleep difficulties.
- Lemon balm – significantly reduces insomnia.
- Valerian – one double-blind study found that it produced “perfect” sleep for 44% of participants and improved sleep for 89%. However, I don’t like it myself. It made me feel spacey.
- Magnesium, preferably L-threonate – believed to cross the blood-brain barrier without GI side effects. Improves hormonal and electrical sleep patterns.22
- Vitamin D3 – helps regulate sleep patterns. Many sleep disorders are linked to this simple deficiency. Take it early in the day to boost circadian rhythm, in 1,000-5,000 IU doses. A blood test is the best way to determine how much supplemental D you need.
- Stevens, RG. Review and commentary: electric power use and breast cancer: a hypothesis. Am J Epidemiol. 1987;125(4):556-561. Kloog I, Haim A, Stevens RG, Barchana M, Portnov BA. Light at night co-distributes with incident breast but not lung cancer in the female population of Israel. Chronobiol Int. 2008;25(1):65-81.
- Kloog I, Haim A, Stevens RG, Barchana M, Portnov BA. Light at night co-distributes with incident breast but not lung cancer in the female population of Israel. Chronobiol Int. 2008;25(1):65-81.
- Portnov BA, Stevens RG, Samociuk H, Wakefield D, Gregorio DI. Light at night and breast cancer incidence in Connecticut: An ecological study of age group effects. Sci Total Environ. 2016;572:1020-1024.
- Kim KY, Lee E, Kim YJ, Kim J. The association between artificial light at night and prostate cancer in Gwangju City and South Jeolla Province of South Korea. Chronobiol Int. 2017;34(2):203-211.
- Burke, T. M. et al. Effects of caffeine on the human circadian clock in vivo and in vitro. Sci Transl Med 7, 305ra146 (2015).
- E. J. W. Van Someren. “Circaadian and sleep disturbances in the elderly.” Experimental Gerontology, Volume 35, Issues 9-10, December 2000, pages 1229-1237.
- University of Pittsburgh Medical Center. “Deterioration of Sleep During Middle Age Related to Changes in the Biological Clock.” Science Daily, 25 June 1998.
- center for the Advancement of Health, 2003, February 4.