How Sleeping Can Affect Your Immune System

By Dr. Mercola

Researchers have learned that 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 to keep your body running smoothly by controlling temperature and the release of hormones.

It's well known that lack of sleep can increase your chances of getting sick. A new study shows just how direct that connection is.

The research 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.

Interestingly, when the researchers induced sepsis, the severity of the disease was dependent on the timing of the induction. Severity directly correlated with cyclical changes in TLR9.

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 am and 6 am.

Furthermore, they also discovered that when mice were vaccinated when TLR9 was peaking, they had an enhanced immune response to the vaccine. The researchers believe vaccine effectiveness could be altered depending on the time of day the vaccination is administered...

According to study author Erol Fikrig, professor of epidemiology at the Yale School of Medicineⁱ:

"These findings not only unveil a novel, direct molecular link between circadian rhythms and the immune system, but also open a new paradigm in the biology of the overall immune response with important implications for the prevention and treatment of disease. Furthermore, patients in the ICU often have disturbed sleep patterns, due to noise, nocturnal light exposure and medications; it will be important to investigate how these factors influence TLR9 expression levels and immune responses."

Lack of Sleep Worsens Stress-Related Immune Depression

One of the first studies to provide direct evidence linking sleep with the human stress-immune relationship dates back to 1998ⁱⁱ. Stress is also known to interfere with immune system function, and has been found to increase susceptibility to the common cold and slow wound healing.

In that 1998 study, the researchers discovered that people who were more likely to awaken during the first sleep cycle also tended to have lower levels of natural killer cells (NKC). Overall, the age of the patient was the greatest determinant of NKC level, but sleep disturbances were responsible for about 12 percent of the variance in NKC level.

Are You Living in Sync with Your Natural Body Clock?

Sleeping well is one of the cornerstones of optimal health, and if you ignore your poor sleeping habits, you will, in time, pay a price. In general, you will feel best and maintain optimal health when your lifestyle is in line with your circadian rhythm. It's wise to establish healthful routines of eating, exercising and sleeping, and to stick to them every day, including the weekends.

Unfortunately, sleep deprivation is such a chronic condition these days that you might not even realize you suffer from it. Your circadian rhythm has evolved over many years to align your physiology with your environment. However, it operates under the assumption that you are behaving as your ancestors did. Historically, humans have slept at night and stayed awake during the day. If you stay up late at night, depriving yourself of sleep, you send conflicting signals to your body.

As a result, you body gets confused and doesn't know whether it should be producing chemicals to help you sleep, or gear up for the beginning of a new day.

Melatonin is another chemical closely tied to your circadian rhythm. It's a pineal hormone and a very potent antioxidant, created in your brain during sleep.

Among its many functions, it slows the production of estrogen and is well known to suppress tumor development, which is why insomnia may increase your risk of cancer. Melatonin also helps suppress harmful free radicals. Melatonin production can be severely disrupted simply by exposing yourself to bright light late at night. Just switching a bedside lamp on and off in an otherwise pitch-black room produces a drop in melatonin levels. This is why it's so important to turn off the lights as the evening wears on, and avoid watching TV and working on the computer late at night.

How Sleep Influences Your Physical Health

Without good sleep, optimal health may remain elusive, even if you eat well and exercise (although those factors will tend to improve your ability to sleep better). Aside from directly impacting your immune function, another explanation for why poor sleep can have such varied detrimental effects on your health is that your circadian system "drives" the rhythms of biological activity at the cellular level. Hence disruptions tend to cascade outward throughout your entire body. For example, besides impairing your immune function and raising your cancer risk, interrupted or impaired sleep can also:

Increase your risk of heart disease.	Harm your brain by halting new cell production. Sleep deprivation can increase levels of corticosterone (a stress hormone), resulting in fewer new brain cells being created in your hippocampus.
Aggravate or make you more susceptible to stomach ulcers.	Contribute to a pre-diabetic state, making you feel hungry even if you've already eaten, which can wreak havoc on your weight.
Raise your blood pressure.	Contribute to premature aging by interfering with your growth hormone production, normally released by your pituitary gland during deep sleep (and during certain types of exercise, such as high intensity interval training).
Worsen constipation.	Increase your risk of dying from any cause.

Furthermore, lack of sleep can further exacerbate chronic diseases such as:

Parkinsons	Alzheimers	Multiple Sclerosis (MS)
Gastrointestinal tract disorders	Kidney disease	Behavioral problems in children

Are Sleeping Pills a Good Option When You Can't Fall Asleep?

If you have trouble sleeping, you're not alone. According to the National Sleep Foundation's (NSF) 2010 "Sleep in America Poll," only four in 10 respondents said they got a good night's sleep every night, or almost every night, of the weekⁱⁱⁱ. But please don't make the mistake of resorting to sleeping pills. At best, they're ineffective. At worst, they can be dangerous.

According to U.S. Food and Drug Administration (FDA) data, over-the-counter sleep products such as Tylenol PM and Excedrin PM don't offer any significant benefit to patients. In 2007, an analysis of sleeping pill studies financed by the National Institutes of Health (NIH) found that sleeping pills like Ambien, Lunesta, and Sonata reduced the average time to go to sleep by just under 13 minutescompared with sugar pills -- hardly a major improvement.

You'd be far better off putting your money toward authentic solutions to help you sleep, like installing black-out drapes in your bedroom, than on sleeping pills, as they may actually make it more difficult for you to get a good night's rest naturally.

If anything, you could consider taking a melatonin supplement, which will help boost sleepiness.

Ideally it is best to increase your melatonin levels naturally, of course, by exposing yourself to bright sunlight in the daytime (along with full spectrum fluorescent bulbs in the winter) and complete darkness at night. If you do this regularly, you will promote proper functioning of your natural circadian rhythm, which is essential for a proper sleep cycle. However, if that isn't possible, you can consider a melatonin supplement. It's is a completely natural substance, made by your body, and has many health benefits in addition to sleep. In scientific studies, melatonin has been shown to increase sleepiness, help you fall asleep more quickly and stay asleep, decrease restlessness, and reverse daytime fatigue. I prefer to use a sublingual melatonin product because it is absorbed much faster and therefore works more quickly.

Keep in mind you typically only need a very minute amount. Taking higher doses, such as 3 mg, can sometimes have the reverse effect. So start with as little as 0.25mg or 0.5mg and play around with it to see what dosage works best for you.

How to Optimize Your Sleep

Below are several of my top guidelines for promoting good sleep. For a comprehensive sleep guide, please see my article 33 Secret's to a Good Night's Sleep.

1. Avoid watching TV or using your computer at night—or at least about an hour or so before going to bed—as these technologies can have a significantly detrimental impact on your sleep. TV and computer screens emit blue light; nearly identical to the light you're exposed to outdoors during the day. This tricks your brain into thinking it's still daytime, thereby shutting down melatonin secretion.

Under normal circumstances, your brain starts secreting melatonin between 9 or 10 pm, which makes you sleepy. When this natural secretion cycle is disrupted, due to excessive light exposure after sunset, insomnia can ensue.

2. Sleep in complete darkness, or as close to it as possible. Even the slightest bit of light in the room can disrupt your internal clock and your pineal gland's production of melatonin and serotonin. Even the tiniest glow from your clock radio could be interfering with your sleep. So close your bedroom door, and get rid of night-lights. Refrain from turning on any light at all during the night, even when getting up to go to the bathroom. Cover up your clock radio.

Make sure to cover your windows—I recommend using blackout shades or drapes.

3. Keep the temperature in your bedroom no higher than 70 degrees F. Many people keep their homes and particularly their upstairs bedrooms too warm. Studies show that the optimal room temperature for sleep is between 60 to 68 degrees. Keeping your room cooler or hotter can lead to restless sleep. This is because when you sleep, your body's internal temperature drops to its lowest level, generally about four hours after you fall asleep. Scientists believe a cooler bedroom may therefore be most conducive to sleep, since it mimics your body's natural temperature drop.
4. 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 for sleep.
5. Check your bedroom for electro-magnetic fields (EMFs). These can disrupt your pineal gland and the production of melatonin and serotonin, and may have other negative effects as well. To do this, you need a gauss meter. You can find various models online, starting around $50 to $200. Some experts even recommend pulling your circuit breaker before bed to shut down all power in your house.
6. Move alarm clocks and other electrical devices away from your bed. If these devices must be used, keep them as far away from your bed as possible, preferably at least three feet. This serves at least two functions. First, it can be stressful to see the time when you can't fall asleep, or wake up in the middle of the night. Secondly, the glow from a clock radio can be enough to suppress melatonin production and interfere with your sleep.

Cell phones, cordless phones and their charging stations should ideally be kept three rooms away from your bedroom to prevent harmful EMF's.

7. Avoid using loud alarm clocks. It is very stressful on your body to be suddenly jolted awake. If you are regularly getting enough sleep, an alarm may even be unnecessary.

I gave up my alarm clock years ago and now spontaneously awake without an alarm. On those rare occasions that I do need to get up early to catch a flight, I have used a sun alarm clock. The Sun Alarm™ provides an ideal way to wake up each morning if you can't wake up with the REAL sun. Combining the features of a traditional alarm clock (digital display, AM/FM radio, beeper, snooze button, etc) with a special built-in light that gradually increases in intensity, this amazing clock simulates a natural sunrise. It also includes a sunset feature where the light fades to darkness over time, which is ideal for anyone who has trouble falling asleep.