Lack of Sleep Can Quadruple Your Risk of Catching a Cold

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September 17, 2015 | 231,773 views

Story at-a-glance

  • Sleeping less than six hours per night can increase your risk of catching a cold by 400 percent
  • Sleep deprivation and stress have the same effect on your immune system; both raise white blood cell counts, which is typically a sign of disease
  • Helpful tips and novel tools to help you optimize your sleep, as well as additional guidelines for cold and flu prevention are included

By Dr. Mercola

Sleep deprivation is extremely common and can weaken your immune system, accelerate tumor growth, accelerate diabetes, and impair all aspects of your cognition. And that's just the short list of side effects.

Now that we're moving closer toward cold and flu season, you would be wise to address your sleeping habits to ward off those banes of wintertime. Research shows sleeping less than six hours per night quadruples your risk of catching a cold.

According to National Sleep Foundation survey data on how much sleep Americans get, as many as one in five people get less than six hours of sleep per night.

 A 2013 Gallup poll1 suggests this number may be closer to 40 percent. If you care about your health, don't be in this category of short sleepers...

Lack of Sleep Increases Your Risk of Catching Cold, and More

According to recent research,2,3,4,5 adults who sleep less than six hours a night have a four times higher risk of catching a cold when directly exposed to the virus than those who get at least seven hours. 

Sleeping less than five hours per night resulted in a 4.5 times higher risk.  Interestingly, they found that sleep was more important than any other factor when it came to protecting against the cold virus, including stress levels, age, and smoking.

According to the lead author:


As noted by Dr. Nathaniel F. Watson, president of the American Academy of Sleep Medicine:6

"This study reinforces the notion that sleep is just as important to your health as diet and exercise. People need to view sleep as a tool to achieve a healthy life, rather than as something that interferes with all their other activities."

Lack of Sleep Impairs Your Body's Insulin Sensitivity


In fact, controlling insulin levels is one of the most powerful ways to reduce your risk of chronic diseases, including high blood pressure, heart disease, and cancer. The increase in insulin-related diseases we're now seeing is likely related to a lack of sleep too.

So if you are having trouble losing weight or struggling with diabetes, it's imperative that you optimize your sleep, as failure to do so could make it very unlikely you will ever be able to get these problems under control.

Lack of Sleep Decimates Your Immune Function

The fact that lack of sleep dramatically raises your chances of catching a cold makes sense when you consider the influence sleep has on your general immune function.

Previous research published in the journal Sleep demonstrates that sleep deprivation has the same effect on your immune system as physical stress.7 White blood cell counts increase when you're sleep deprived, and this is the same type of response you typically see when you're sick or stressed.

In a nutshell, whether you're physically stressed, sick, or sleep deprived, your immune system becomes hyperactive and starts producing white blood cells —   your body's first line of defense against foreign invaders like infectious agents.

Elevated levels of white blood cells are typically a sign of disease. The American Academy of Sleep Medicine and the Sleep Research Society, which recently published updated sleep guidelines based on the available research, warn that sleeping less than seven hours per night is also associated with:

Weight gain Diabetes Hypertension
Heart disease Stroke Depression
Premature death Weakened immune function Pain
Impaired performance and cognition Increased errors Heightened accident risk

The results from more than 300 studies suggest that, to protect your health, you need right around eight hours of sleep per night; and at least a minimum of seven. This applies to adults and seniors alike.

School-aged children need anywhere from nine to 11 hours, and teenagers need eight to 10 hours of sleep per night.

Your Immune System Needs Melatonin for Optimal Function

For the past century or so, the developed world has been performing an open-ended experiment on itself by lengthening its days and shortening its nights in an effort to become a 24-hour per day, ever-productive society.

But light pollution generated by modern technologies is taking a heavy biological toll. Your body contains a number of biological clocks, which are governed by Earth's cycles of light and darkness.

In short, you were built to be active and restful in accordance to the rising and setting of the sun, and ignoring this biological imperative has consequences that you cannot "will" away.

Your main master clock resides in the suprachiasmatic nucleus of your brain (SCN), which is part of your hypothalamus. Based on signals of light and darkness, your SCN tells your pineal gland when it's time to secrete melatonin — a powerful antioxidant and free radical scavenger that helps combat inflammation.

Artificial lighting disrupts your biological clock and melatonin production, which in turn impairs your immune function. In fact, melatonin is so integral to your immune system that a lack of it causes your thymus gland, a key component of your immune system, to atrophy.  

Melatonin also helps protect your brain health, and is a very potent anti-cancer agent. Cells throughout your body — even cancer cells — have melatonin receptors. So when melatonin makes its nightly rounds (its production peaks during the night), cell division slows.

When this hormone latches onto a breast cancer cell, it has been found to counteract estrogen's tendency to stimulate cell growth. It also triggers cancer cell apoptosis (self destruction), and interferes with the new blood supply tumors require for their rapid growth (angiogenesis).

It's also been well-established that night shift workers have an increased risk of weight gain, diabetes, and cancer. So the health consequences of disrupted sleep can certainly be far more dire than elevating your risk for the common cold...

How to Optimize Your Sleep

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

Get BRIGHT sun exposure during the day, every dayYour 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. To help your circadian system to reset itself, make sure to get at least 10 to 15 minutes of morning sunlight. This will send a strong message to your internal clock that day has arrived, making it less likely to be confused by weaker light signals later on.

Avoid watching TV or using your computer at nightLight emitting technologies can have a significantly detrimental impact on your sleep, so avoid them for at least an hour or so before going to bed. 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.

Sleep in complete darkness, or as close to it as possibleEven the slightest bit of light in the room can disrupt your internal clock and your pineal gland's production of melatonin. 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. An eye mask is an inexpensive alternative.

If you need a nighttime navigation light, install a low-wattage yellow, orange, or red light bulb. Light in these bandwidths does not shut down melatonin production in the way white and blue bandwidth light does. Salt lamps are handy for this purpose. You can also download a free application called f.lux that automatically dims your monitor or screens at night.
Keep the temperature in your bedroom below 70 degrees FMany people keep their homes too warm. Studies show 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.
Take a hot bath 90 to 120 minutes before bedtimeThis 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.


Helpful Tools to Improve Your Sleep

To make sure you're getting enough sleep, you need to make sure you're going to bed early enough. If you have to get up at 6:30am, you're not going to get enough sleep if you go to bed after midnight. A fitness tracker that tracks both daytime movement and sleep can be a helpful tool, allowing you to get a better picture of how much sleep you're actually getting. Chances are, you're getting at least 30 minutes less shut-eye than you think, as people typically don't fall asleep as soon as their head hits the pillow.

Another novel invention is an app called Sleep Genius8,9 available for Android, and iOS. It's a free application based on NASA research to help astronauts sleep better. It uses sounds scientifically composed to trigger your brain into getting to sleep faster, promoting deeper and longer sleep than normal. You can set it for a specific time, or let it play all night. Its Revive Cycle Alarm gradually wakes you up without harsh alarms. If you're using it on your smartphone, be sure the phone is as far away from your bed as possible to avoid EMF exposure.

Additional Guidelines for Natural Cold and Flu Prevention

It's important to remember that your immune system is your primary line of defense against any virus, so keeping your immune function high should be at the top of your list if you want to avoid the flu. According to the featured study, sleep may be the number one lifestyle factor that can increase or decrease your risk, so be sure to get enough rest. Just like it becomes harder for you to get your daily tasks done if you're tired, if your body is overly fatigued it will be harder for it to fight the cold or flu virus.

In addition to optimizing your sleep quality and making sure you're getting about eight hours a night, the following guidelines can help keep your immune system in optimal working order so you're far less likely to acquire the infection when people around you start coughing and sneezing.

Avoid processed foods and sweet beveragesSugar impairs the function of your immune system almost immediately. Be aware that sugar (typically in the form of high fructose corn syrup) is present in foods you may not suspect, like ketchup and fruit juice.
Optimize your gut floraAbout 80 percent of your immune system resides in your gut, so optimizing your gut microbiome is really important. The best way to do this is to avoid sugars, processed foods, and most grains, and replacing them with healthy fats and taking regular amounts of fermented foods. This can radically improve the function of your immune system.
Exercise regularlyWhen you exercise, you increase your circulation and your blood flow throughout your body. The components of your immune system are also better circulated, which means your immune system has a better chance of finding an illness before it spreads. Be sure to incorporate high-intensity interval exercises like Peak Fitness into your routine.
Take a high quality animal-based omega-3 fatIncrease your intake of healthy and essential fats like the omega-3 found in krill oil, which is crucial for maintaining health. It's also important to avoid damaged omega-6 oils found in processed foods, as having a lopsided omega-3 to omega-6 ratio can seriously damage your immune response.
Remember basic hygiene measures, such as washing your handsWashing your hands will decrease your likelihood of spreading a virus to your nose, mouth or other people. Be sure you don't use antibacterial soap for this – antibacterial soaps are completely unnecessary, and they cause far more harm than good by promoting antibacterial resistance. All you need is a gentle soap and warm water.

Address your stressWe all face some stress every day, but if stress becomes overwhelming, then your body will be less able to fight off illness. If you feel stress is taking a toll on your health, consider using an energy psychology tool such as the Emotional Freedom Techniques, which is remarkably effective in relieving stress associated with all kinds of events, from work to family to trauma.
Use natural immune boostersExamples include oil of oregano, olive leaf extract, garlic, and colloidal silver.

[+]Sources and References [-]Sources and References

  • 1 Gallup Poll 2013
  • 2 Sleep September 2015: 38(9); 1353-1359
  • 3 WebMD August 31, 2015
  • 4 Time August 31, 2015
  • 5 Guardian August 31, 2015
  • 6 New York Times September 2, 2015
  • 7 Sleep 2012;35(7):933-940
  • 8
  • 9 LiveMint September 8, 2015