WARNING!
This is an older article that may not reflect Dr. Mercola’s current view on this topic. Use our search engine to find Dr. Mercola’s latest position on any health topic.
By Dr. Mercola
The bacteria living in your gut do more than help your body digest and metabolize the food you eat. A myriad of research studies demonstrate these bacteria are integral to your health and well-being, and may positively influence the activity of hundreds of your genes and your immune system.
When you add friendly bacteria to your intestinal tract they are called probiotics. Another way of impacting the friendly bacteria in your gut is to provide them with the nutrients they need to multiply. These nutrients are called prebiotics.
Prebiotics are found primarily in fiber-rich foods. Friendly bacteria thrive on indigestible fiber. Inulin is one type of water-soluble fiber found in onions, garlic, leeks and asparagus that help nourish the beneficial bacteria in your gut.
Now researchers have found dietary prebiotics have a significant effect on rapid-eye-movement (REM) and non-rapid-eye-movement (NREM) sleep cycles, which may positively affect your sleep quality.1
Prebiotics Study
Researchers studied the effect of prebiotics on gut health and REM sleep of young rats. The test animals were given a diet rich in prebiotics starting when they were 3 weeks old.2
The researchers noted that in previous studies, results suggested daily stress could alter your gut microbiome in a way that would alter your sleep-wake cycle. Their goal was to determine if using prebiotics might help improve sleep quality under stress.
The rats were fed a manufactured diet containing prebiotic fiber or a control diet for four weeks. After the first four weeks the researchers analyzed the excrement and found those eating prebiotics had an increase in beneficial gut bacteria, compared to the control group.3
As the friendly bacteria metabolize the prebiotic fiber, they not only grow and multiply but also excrete a metabolite beneficial to your brain health.4 Rats eating the diet rich in prebiotics also spent more time in restful and restorative NREM sleep than those eating the control diet. The researchers wrote:5
"Given that sufficient NREM sleep and proper nutrition can impact brain development and function and that sleep problems are common in early life, it is possible that a diet rich in prebiotics started in early life could help improve sleep, support the gut microbiota and promote optimal brain/psychological health."
The test group also benefited when stressed. Researchers found they spent more time in REM sleep after being stressed, which is important for promoting recovery.6 Prior research has found people who get more REM sleep after a significant trauma are less likely to suffer post-traumatic stress disorder.7
Prebiotics May Improve a Depleted Gut
While fiber is an excellent prebiotic for friendly bacteria, sugar and carbohydrates are the nutrients your unfriendly bacteria use to grow and multiply. If you eat a typical Western diet, high in processed foods and refined carbohydrates, your gut microbiome may not have enough beneficial bacteria to keep you healthy.
The test group of rats in the study did not experience a stress disruption of their gut microbiome, as did the control group of rats, and returned to normal sleep patterns more quickly than the control group as well.8
The results of this study only contribute to current research demonstrating the importance of gut health on inflammation, obesity, depression, metabolic syndrome and insulin resistance.
Although all prebiotics are fiber, not all fiber has a prebiotic effect on friendly bacteria.9 To be classified as a prebiotic the fiber must resist gastric acidity, resist absorption in the upper gastrointestinal tract, be fermented by intestinal flora and stimulate the growth or activity of beneficial bacteria.
The role of fiber in the diet has also been associated with improved bowel movements and reducing risk factors with cardiovascular disease, weight management, digestive health and immune function.
Increasing your intake of foods rich in prebiotic fiber may help improve your gut health, your sleep-wake cycles and reduce your risk for health conditions affected by lack of fiber.
Get Prebiotics Daily
As the benefits of prebiotics are becoming better known, food manufacturers are climbing on the bandwagon, advertising the benefits of fiber in their products.
However, as with most dietary choices, the best prebiotic fiber is found in raw, whole foods, since most manufactured foods also contain some form of sugar, which feeds your unfriendly bacteria.
It is not always possible to eat enough foods rich in prebiotic fiber to nourish your beneficial bacteria. If you're looking for a healthy way to supplement your fiber intake, organic whole husk psyllium is a simple, cost-effective way to do it.
Taking it three times a day could add as much as 18 grams of dietary fiber (soluble and insoluble) to your diet, which brings you quite close to the recommended minimum of 50 grams per 1,000 calories consumed when added to a healthy, veggie-rich diet.
Please keep in mind that psyllium is a heavily sprayed crop, which means many sources are contaminated with pesticides, herbicides and fertilizers. For this reason, be sure to use only organic psyllium husk, and ensure it's 100 percent pure.
Many supplement brands use synthetic or semi-synthetic active ingredients that do not contain psyllium, such as methylcellulose and calcium polycarbophil. The following whole foods help add prebiotic fiber to your diet and improve the health of your microbiome, thus improving your overall health.10,11,12
✓ Onions |
✓ Leeks |
✓ Garlic |
✓ Chicory root |
✓ Banana |
✓ Apples |
✓ Konjac root |
✓ Burdock root |
✓ Jicama |
✓ Seaweed |
✓ Jerusalem artichokes |
✓ Shallots |
✓ Asparagus |
✓ Beetroot |
✓ Fennel bulb |
✓ Green peas |
✓ Snow peas |
✓ Savoy cabbage |
✓ Chickpeas |
✓ Lentils |
✓ Red kidney beans |
✓ Nectarines |
✓ Persimmon |
✓ Tamarillo |
✓ Grapefruit |
✓ Pomegranate |
✓ Couscous |
✓ Cashews |
✓ Pistachio nuts |
✓ Breast milk |
Dangers of Stress
Stress not only can negatively impact your sleep quality, but has been implicated in the development of other health conditions such as anxiety, heart disease and stroke.
Renowned author and award-winning neurobiologist Robert Sapolsky, Ph.D., speaks about this in the documentary, "Stress: Portrait of a Killer," which was jointly produced by National Geographic and Stanford University, where Sapolsky is a professor.
In the film, Sapolsky warns us that13 "Stress is not a state of mind ... it's measurable and dangerous, and humans can't seem to find their off-switch." Your stress response saves lives when it enables you to run from predators or rescue someone from a burning building.
But, this same "life-saving" reaction becomes chronic when you need to cope with the rising cost of fuel, fear of public speaking or managing a difficult work situation. The documentary demonstrates how stress may shrink your brain, add fat to your belly and even shorten your life.
Stress also has a significant impact on the quality of your sleep, which in turn has an impact on your ability to cope with stress. It's a vicious cycle that may increase your risk of suffering negative health conditions.
Importance of Quality Sleep
You've probably experienced working through a day after a poor night of sleep. You feel groggy, you may not have been able to think as clearly and you likely spent the day yawning. Lack of sleep has a significant impact on your cognitive functioning,14 and driving on five hours of sleep or less is like driving drunk to your brain.15
Quality sleep is not only important to your immediate health, mood, energy and daily functioning, but a chronic lack of sleep has a significant impact on your long-term health as well. Chronic loss of sleep puts you at risk for:16
✓ Heart disease |
✓ Heart failure |
✓ Diabetes |
✓ Irregular heart rate |
✓ High blood pressure |
✓ Stroke |
✓ Loss of sex drive |
✓ Depression |
✓ Obesity |
✓ Impaired judgment |
✓ Increased risk of dementia17 |
✓ Increased risk of accidents or injury |
Tips for Quality Sleep
Eating enough foods rich in prebiotic fiber or taking an additional supplement is one way to help improve the quality of your sleep. Here are several more tips, that when combined, may help you enjoy a quality eight or nine hours of sleep each night and effectively reduce your potential risk for illnesses associated with chronic sleep deprivation. For more tips to a restful night of sleep see my previous article, "16 Chronological Tips to Improve Your Sleep."
✓ Enjoy Exposure to Bright Sunlight Every Morning
Exposure to bright light first thing in the morning stops production of the sleep-inducing hormone melatonin and signals to your body that it's time to wake up. Outdoor sunlight is best, so you might even want to take a quick walk outside. |
✓ Daily Exercise
Exercise leads to better sleep at night. Many people schedule their full workouts for morning, which makes it easier to also exercise while fasting (an added benefit). If you don't have time for a full workout, at least do some quick stretching or bodyweight exercises. |
✓ Daily Walk Outside After Lunch
Not only will this increase in physical activity help you sleep later, but taking your walk outdoors gives you more exposure to bright sunlight. Light intensity is measured in lux units, and on any given day, the outdoor lux units will be around 100,000 at noon.
Indoors, the typical average is somewhere between 100 to 2,000 lux units — about two orders of magnitude less. The brightness of the light matters, because 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 relative darkness all day long, it can't appreciate the difference and will not optimize your melatonin production. This, in turn, can have some rather significant ramifications for your health and sleep.
I take a one-hour walk every day in the bright sunlight on the beach, so along with boosting my vitamin D, I also anchor my circadian rhythm at the same time and I rarely ever have trouble sleeping. |
✓ Cut the Caffeine in Early Afternoon
If you're a coffee drinker, take your last caffeinated sip in the early afternoon (this applies to caffeinated soda, too). The caffeine can linger in your body for hours, blocking a brain chemical called adenosine triphosphate (ATP) that would otherwise help you to fall asleep. |
✓ Light Dinner and No Food Three Hours Before Bed
If you eat a heavy meal too close to bedtime, your body will have to devote energy to digesting your food when it should be recharging during sleep. As part of Peak Fasting, I also recommend that you stop eating three hours before bed and don't have your first meal until 13 to 18 hours later. |
✓ Take 15 Minutes to Unwind
If you're stressed, it's harder to fall asleep and stay asleep. Taking 15 minutes (at least) at the end of each day to relax may help your sleep significantly. You may try listening to music, journaling, meditation, chatting with a neighbor or the Emotional Freedom Techniques (EFT). Do whatever works best for you. |
✓ Avoid Blue Light at Night
In the evening (around 8 p.m.), you'll want to dim your lights and turn off electronic devices. Normally, your brain starts secreting melatonin between 9 p.m. and 10 p.m., and these devices emit light that may stifle that process. After sundown, shift to a low-wattage bulb with yellow, orange or red light if you need illumination.
A salt lamp illuminated by a 5-watt bulb is an ideal solution that will not interfere with your melatonin production. If using a computer or smartphone, install blue light-blocking software like Iris, which is an improvement over f.lux. The program automatically alters the color temperature of your screen as the day goes on, pulling out the blue wavelengths as it gets late.
The easiest solution, however, is to simply use amber-colored glasses that block blue light. I found an Uvex model (S1933X) on Amazon that costs less than $10 and works like a charm to eliminate virtually all blue light.
This way you don't have to worry about installing programs on all your devices or buying special light bulbs for evening use. Once you have your glasses on, it doesn't matter what light sources you have on in your house. |
✓ Reduce Noise, Temperature and Light
Noise louder than a normal conversation may stimulate your nervous system and keep you awake. You may want to use a fan or other form of white noise to drown out noise disturbances while you sleep.
Thermoregulation — your body's heat distribution system — is strongly linked to sleep cycles. 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.
Once you're ready to climb into bed, make sure your bedroom is pitch black. The slightest bit of light in your bedroom can disrupt your body's clock and your pineal gland's melatonin production. You may want to cover your windows with drapes or blackout shades to achieve this and, if this isn't possible, wear an eye mask. |
Dos and Don'ts to Optimizing Your Gut Microbiome
Feeding your beneficial bacteria with prebiotics is more effective when you have a variety of friendly bacteria growing in your intestinal tract. Optimizing your gut microbiome may be one of the most important things you can do for your health. It is critical for a well-functioning immune system, and to help you normalize your sleep-wake cycles.
However, while vital, it is not very complicated. You will need to take proactive steps to implement certain key strategies and actively avoid other factors. To optimize your gut microbiome, consider the following recommendations:
| Do: |
Avoid: |
Do: Eat plenty of fermented foods. Healthy choices include lassi, fermented grass-fed organic milk such as kefir, natto (fermented soy) and fermented vegetables.
If you ferment your own, consider using a special starter culture that has been optimized with bacterial strains that produce high levels of vitamin K2.
This is an inexpensive way to optimize your K2, which is particularly important if you're taking a vitamin D3 supplement. |
Avoid: Antibiotics, unless absolutely necessary (and when you do, make sure to reseed your gut with fermented foods and/or a probiotic supplement).
While researchers are looking into methods that might ameliorate the destruction of beneficial bacteria by antibiotics,18,19 your best bet is likely always going to be reseeding your gut with probiotics from fermented and cultured foods and/or a high-quality probiotic supplement. |
Do: Take a probiotic supplement. Although I'm not a major proponent of taking many supplements (as I believe the majority of your nutrients need to come from food), probiotics are an exception if you don't eat fermented foods on a regular basis |
Avoid: Conventionally raised, non-grass-fed meats and other animal products, as CAFO animals are routinely fed low-dose antibiotics, plus genetically engineered grains loaded with glyphosate, which is widely known to kill many bacteria. |
Do: Boost your soluble and insoluble fiber intake, focusing on vegetables, nuts and seeds, including sprouted seeds. |
Avoid: Chlorinated and/or fluoridated water. |
Do: Get your hands dirty in the garden. Germ-free living may not be in your best interest, as the loss of healthy bacteria can have wide-ranging influence on your mental, emotional and physical health.
Exposure to bacteria and viruses can help strengthen your immune system naturally, providing long-lasting immunity against disease.
Getting your hands dirty in the garden can help reacquaint your immune system with beneficial microorganisms on the plants and in the soil.
According to a recent report,20 lack of exposure to the outdoors can in and of itself cause your microbiome to become "deficient." |
Avoid: Processed foods. Excessive sugars, along with otherwise "dead" nutrients, feed pathogenic bacteria.
Food emulsifiers such as polysorbate 80, lecithin, carrageenan, polyglycerols and xanthan gum also appear to have an adverse effect on your gut flora.21
Unless 100 percent organic, they may also contain genetically engineered ingredients that tend to be heavily contaminated with pesticides such as glyphosate.
Artificial sweeteners have also been found to alter gut bacteria in adverse ways.22 |
Do: Open your windows. For the vast majority of human history the outside was always part of the inside, and at no moment during our day were we ever really separated from nature.
Today, we spend 90 percent of our lives indoors. And, although keeping the outside out does have its advantages it has also changed the microbiome of your home.
Research23 shows that opening a window and increasing natural airflow can improve the diversity and health of the microbes in your home, which in turn benefit you. |
Avoid: Agricultural chemicals, glyphosate (Roundup) in particular is a known antibiotic and will actively kill many of your beneficial gut microbes if you eat and foods contaminated with Roundup. |
Do: Wash your dishes by hand instead of in the dishwasher. Research has shown that washing your dishes by hand leaves more bacteria on the dishes than dishwashers do, and that eating off these less-than-sterile dishes may actually decrease your risk of allergies by stimulating your immune system. |
Avoid: Antibacterial soaps, as they too kill off both good and bad bacteria, and contribute to the development of antibiotic-resistance. |