By Dr. Mercola
Your body is designed to sleep in the evening when the sun goes down, and increasing research is confirming that if you disrupt this biological cycle your health will indeed suffer.
The problem is that, in the 21st century, many people ignore their body's internal clocks, either by necessity (working the night shift) or choice (staying up late surfing the Web or watching TV).
But late nights aren't the only culprits interfering with circadian rhythms. Jet lag and daytime naps may also wreak havoc on your body's ability to function optimally, even interfering with the activity of your genes.
Daytime Sleeping, Jet Lag Interfere with Your Genes
Research published in Proceedings of the National Academy of Sciences (PNAS) revealed the high price you might pay for disrupting your normal day/night biological clock.
The researchers changed the participants' sleep patterns so they were about 12 hours out of sync in order to simulate the effects of jet lag or working the night shift.
When blood tests were given, the results showed decreased gene expression, with up to one-third of participants' genes measurably altered by the disrupted sleep cycles.1 According to the researchers:
"Genes and processes affected included those at the core of circadian rhythm generation and gene expression. The data have implications for understanding the negative health outcomes of disruption of the sleep–wake cycle."
Such disruptions have already been linked to heart disease, obesity, diabetes, cancer, and other chronic health conditions, raising serious concerns for people who regularly sleep during the day and/or stay awake at night. This includes not only those working the night shift but also frequent travelers (jet lag), college students, regular daytime nappers, and late night owls.
Past research has similarly shown that just one week of insufficient sleep alters gene expression, affecting genes involved in immune and stress responses, regulation of gene expression and more.2
Your Circadian Rhythm May Control Certain Genes
Circadian rhythms—the 24-hour cycles known as your internal body clock—are involved in everything from sleep to weight gain, mood disorders, and a variety of diseases.
Your body actually has many internal clocks—in your brain, lungs, liver, heart, and even your skeletal muscles—and they all work in concert to keep your body running smoothly by controlling temperature and the release of hormones. They may also play a critical role in the expression of your genes, for better or for worse.
For instance, one study found that the circadian clocks of mice control an essential immune system gene that helps their bodies sense and ward off bacteria and viruses. When levels of that particular gene, called toll-like receptor 9 (TLR9), were at their highest, the mice were better able to withstand infections.3
Interestingly, when the researchers induced sepsis, the severity of the disease was dependent on the timing of the induction. According to the authors, this may help explain why septic patients are known to be at higher risk of dying between the hours of 2 a.m. and 6 a.m.
Separate research also found that when participants cut their sleep from 7.5 to 6.5 hours a night, there were increases in activity in genes associated with inflammation, immune excitability, diabetes, cancer risk, and stress.4
From the results of this study, it appears as though sleeping for an extra hour, if you're getting less than seven hours of sleep a night, may be a simple way to boost your health. But the opposite also holds true in that getting just one hour less sleep a night may raise your risk of multiple chronic diseases.
Disrupted Sleep Speeds Up Cancer
Lack of sleep has long been linked to an increased risk of cancer, but new research has revealed one reason why. Among mice given a cancer-inducing treatment, those whose sleep was disrupted developed more aggressive, larger tumors than the well-rested mice.5
Furthermore, it appeared that the immune systems of the sleep-disrupted mice were less effective at fighting the cancer in its early stages. The study's lead researcher explained:6
"It's not the tumor, it's the immune system. Fragmented sleep changes how the immune system deals with cancer in ways that make the disease more aggressive."
Other cancer links have also been found in humans with insufficient sleep. A study published in the journal Cancer, Epidemiology, Biomarkers & Prevention found that men who had trouble sleeping were twice as likely to develop prostate cancer compared to those who slept well.7 Another study found that insufficient sleep may be a contributing factor in both the recurrence of breast cancer and more aggressive forms of breast cancer among post-menopausal women.8
Disrupted melatonin production caused by lack of sleep, or exposure to light at night, has also been shown to increase cancer risk. Melatonin inhibits the proliferation of a wide range of cancer cell types, as well as triggering cancer cell apoptosis (self-destruction).9
The hormone also interferes with the production of new blood vessels by tumors (angiogenesis) required for their rapid growth. Not to mention, poor sleep is associated with an increased risk of insulin resistance and weight gain, which also contribute to cancer development.
In 2007, the World Health Organization (WHO) even announced a decision to classify shift work as a "probable carcinogen."10
That puts the night shift in the same health-risk category as exposure to such toxic chemicals as trichloroethylene, vinyl chloride, and polychlorinated biphenyls (PCBs). If this isn't a testament to the importance of maintaining a normal sleep-wake cycle for human health, I don't know what is!
Frequent Traveler? How You Can Minimize the Impacts of Jet Lag
Whether you're traveling for business or pleasure, when you cross several time zones in a short period of time, your circadian rhythm becomes out of sync with the external environment's clock. So while your body may be telling you it's time to go to sleep, the sun may be rising in your new locale, signaling it's time to wake up and eat breakfast. This internal-external conflict can lead to feelings of being tired and wired at the same time, or it may cause insomnia, fatigue, headaches, irritability, mental fogginess, and more. As the featured study also showed, jet lag may disrupt your gene expression, increasing your risk of chronic disease.
Eventually your body will adjust to the rhythm of its new environment, but experts estimate recovery rates of up to one day for each time zone crossed, which will seriously eat into the time you have at your destination. Further, if you experience jet lag frequently, it could begin to interfere with your long-term health.
In the video above, Dr. Lee Cowden, a well-respected leader and teacher in natural medicine, shares a simple stroking technique you can use to help eliminate the effects of jet lag. As he mentions, this should be done at 11 a.m. (based on the time in your new locale) and again at noon. It will only take a couple of minutes of your time and it costs absolutely nothing. I actually never tried this but I will be in Manila for two weeks, which is 13 time zones from where I live, so it will be a perfect opportunity to try it.
Dr. Cowden also recommends taking melatonin in the evening in your new destination, and I agree. Melatonin has been shown to help people fall asleep faster and stay asleep, experience less restlessness, and prevent daytime fatigue. Keep in mind that only a very small dose is required — typically 0.25 mg or 0.5 mg to start with, and you can adjust it up from there. Taking higher doses, such as 3 mg, can sometimes make you more wakeful instead of sleepier, so adjust your dose carefully.
Additionally, you'll want to increase melatonin levels naturally with exposure to bright sunlight in the daytime. Force yourself to stay awake during the day and mimic your destination's normal routine as much as possible right from the start (taking a red eye flight may also be beneficial, as it allows you to sleep at your normal time). Once in your new destination, go to sleep in the evening, with your melatonin for help if necessary. Magnesium may also be beneficial, as lack of magnesium may play a role in insomnia (and many Americans are magnesium-deficient).
Tips for Getting Your Sleep Cycle Back on Track
If you currently work nights, I would strongly suggest trying to switch your hours, or at the very least restrict your night shift duty to a couple months at a time. This will at least give your body a chance to readjust in between. If it is not possible for you to avoid working the night shift, you can somewhat counter the health effects by keeping to a schedule. By being consistent, your body's clock will eventually adjust to your sleep/wake cycle, and this is LESS damaging than if you constantly change shifts and expect your body clock to adjust.
Next, although day sleeping makes it much more challenging to create a dark environment, it is essential that you make your bedroom pitch-black, even if you're sleeping at noon, as exposure to light squelches the production of melatonin. Even the dim glow from your clock radio could be interfering with your ability to sleep -- and more importantly, your long-term health and risk of developing cancer or other health problems.
Many of the tips for optimizing your circadian rhythm are one in the same with those that will optimize your melatonin production. In order to maintain a healthy circadian rhythm, or reset yours if it's off balance, use the tips that follow. For a comprehensive sleep guide, please see my article 33 Secrets to a Good Night's Sleep.
- Avoid watching TV or using your computer in the evening, at least an hour or so before going to bed. These devices emit blue light, which tricks your brain into thinking it's still daytime. Normally, your brain starts secreting melatonin between 9 and 10 pm, and these devices emit light that may stifle that process. Even the American Medical Association now states:11
"… nighttime electric light can disrupt circadian rhythms in humans and documents the rapidly advancing understanding from basic science of how disruption of circadian rhythmicity affects aspects of physiology with direct links to human health, such as cell cycle regulation, DNA damage response, and metabolism."
- Make sure you get BRIGHT sun exposure regularly. Your pineal gland produces melatonin roughly in approximation to the contrast of bright sun exposure in the day and complete darkness at night. If you are in darkness all day long, it can't appreciate the difference and will not optimize your melatonin production.
- Sleep in complete darkness, or as close to it as possible. Even the slightest bit of light in your bedroom can disrupt your biological clock and your pineal gland's melatonin production. Even the tiniest glow from your clock radio could be interfering with your sleep, so cover your radio up at night or get rid of it altogether. Move all electrical devices at least three feet away from your bed. You may want to cover your windows with drapes or blackout shades.
- Install a low-wattage yellow, orange, or red light bulb if you need a source of light for navigation at night. Light inthese bandwidths does not shut down melatonin production in the way that white and blue bandwidth light does. Salt lamps are handy for this purpose.
- Keep the temperature in your bedroom no higher than 70 degrees F. Many people keep their homes too warm (particularly their upstairs bedrooms). Studies show that the optimal room temperature for sleep is between 60 to 68 degrees.
- Take a hot bath 90 to 120 minutes before bedtime. This increases your core body temperature, and when you get out of the bath it abruptly drops, signaling your body that you are ready to sleep.
- Avoid using loud alarm clocks. Being jolted awake each morning can be very stressful. If you are regularly getting enough sleep, you might not even need an alarm.
- Get some sun in the morning, if possible. Your circadian system needs bright light to reset itself. Ten to 15 minutes of morning sunlight will send a strong message to your internal clock that day has arrived, making it less likely to be confused by weaker light signals during the night. More sunlight exposure is required as you age.
- Be mindful of electromagnetic fields (EMFs) in your bedroom. EMFs can disrupt your pineal gland and its melatonin production, and may have other negative biological effects as well. A gauss meter is required if you want to measure EMF levels in various areas of your home.