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Tag: serotonin

  • Phototherapy and Losing Weight  | NutritionFacts.org

    Phototherapy and Losing Weight  | NutritionFacts.org

    What did randomized controlled trials of phototherapy—bright morning light—for weight loss find? 

    If weakening our circadian rhythm can cause weight gain, might strengthening it facilitate weight loss? You may remember the child’s swing analogy I shared previously. Regular morning meals can give our cycles a little daily push, but the biggest shove comes from our exposure to bright morning light. Similarly, exposure to light at night could be analogous to nighttime eating, as you can see below and at 0:31 in my video Shedding Light on Shedding Weight. 

    Of course, we’ve had candles to illuminate our nights for 5,000 years, but flames from candles, campfires, and oil lamps are “strongly skewed towards the red end of the [light] spectrum; as a result, firelight has much less impact on circadian rhythmicity than electric light.” It’s the shorter blue wavelengths that specially set our circadian clocks. Electric lighting, which we’ve only had for a little over a century, “has gradually changed since the 1960s from an incandescent-bulb form consisting of mainly low-level yellow wavelengths to high-intensity discharge forms,” such as fluorescents and LED lights, “that contain blue wavelengths,” which are more similar to morning sunlight and have the strongest effect on our circadian rhythm.

    Using wrist meters to measure ambient light exposure, researchers found that increased exposure to light in the evening and nighttime correlated with a subsequent increased risk of developing obesity over time. This was presumed to be due to circadian misalignment, but might it instead be a sign of not sleeping as much, and maybe that’s the real reason people grew heavier? This was controlled for in a study of more than 100,000 women, which found that the odds of obesity trended with higher nighttime light exposure independent of sleep duration.

    Compared to women who reported their bedrooms at night were either too dark to see their hand in front of their face or at least dark enough that they couldn’t see across the room, those who reported their bedrooms were light enough to see across the room were significantly heavier. They weren’t all sleeping with nightlights on either. Without blackout curtains on windows, many neighborhoods may be bright enough to cause circadian disruption. Using satellite imagery, scientists have even been able to correlate higher obesity rates with brighter communities. There’s so much light at night these days that, outside of a blackout, the only Milky Way our children will likely ever see is inside a candy wrapper.

    Although sleep quantity could be controlled, what about sleep quality? Maybe people sleeping in bedrooms that aren’t as dim don’t sleep as soundly, leaving them too tired to exercise the next day, for example. You can’t know for sure if nocturnal light exposure is harmful in and of itself until you put it to the test. When that was done, those randomized to exposure to bright light for a few hours in the evenings or exposed even just for a single night suffered adverse metabolic consequences. 

    The more intriguing question then becomes: Can circadian syncing with morning bright light therapy be a viable weight-loss strategy? Insufficient morning light may be the circadian equivalent of skipping breakfast. Indoor lighting is too bright at night, but it may be too dim during the day to robustly boost our daily rhythm. Light exposure from getting outdoors in the morning, even on an overcast day, is correlated to lower body weight compared to typical office lighting, so some doctors started trying “phototherapy” to treat obesity. The first case reports began being published in the 1990s. Three out of four women lost an average of about four pounds over six weeks of morning bright light exposure, but there was no control group to confirm the effect. 

    Ten years later, the first randomized controlled trial was published. Overweight individuals were randomized to an exercise intervention with or without an hour a day of bright morning light. Compared to normal indoor lighting, the bright light group lost more body fat, but it’s possible the light just stimulated them to exercise harder. Studies show that exposure to bright light, even the day prior to exercise, may boost performance. In a handgrip endurance test, exposure to hours of bright light increased the number of contractions until exhaustion from about 770 to 860 the next day. While light-induced improvements in activity or mood can be helpful in their own right, it would be years later still before we finally learned whether the light exposure itself could boost weight loss. 

    Following an unpublished study in Norway purporting to show a dozen-pound weight-loss advantage to eight weeks of 30 minutes of daily daylight (compared to indoor lighting), researchers tried three weeks of 45 minutes of morning bright light compared to the same time sitting in front of an “ion generator” that appeared to turn on but was secretly deactivated. As you can see in the graph below and at 5:08 in my video, the three weeks of light beat out the placebo, but the average difference in body fat reduction was only about a pound. This slight edge didn’t seem to correlate with mood changes, but bright light alone can stimulate serotonin production in the human brain and cause the release of adrenaline-type hormones, both of which could benefit body fat aside from any circadian effects. 

    Regardless of the mechanism, bright morning daylight exposure could present a novel weight-loss strategy straight out of the clear blue sky.  

    I have a whole series on chronobiology. You can see all of the videos on the topic page. The last few are listed below in the related posts and help to paint the full picture of how our environment can affect our circadian rhythms.

    For more on weight loss, you can also check out my recent series in the related posts below, or browse all of my weight loss videos here. 

    Michael Greger M.D. FACLM

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  • Music Is A Turn On Like Sex And Marijuana

    Music Is A Turn On Like Sex And Marijuana

    An anthem of youth and counterculture has been sex, drug and rock and roll.  Since the 60s it has been been part of concerts, colleges, and early post school life.  Deadheads, Blockheads and the Sex Pistols all rode the wave.  Now science agrees music is a turn on like sex and marijuana.

    Now,  landmark research from McGill University in Montreal demonstrates the opioid system in human brains is directly involved in musical enjoyment.

    “This is the first demonstration that the brain’s own opioids are directly involved in musical pleasure,” says cognitive psychologist Daniel Levitin, senior author of the paper.

    RELATED: 4 DJs Share Their Favorite Cannabis Strains

    While previous work by Levitin’s lab and others had used neuroimaging to map areas of the brain which are active during moments of musical pleasure, scientists were able only to infer the involvement of the opioid system.

    “The findings, themselves, were what we hypothesized,” Levitin said. “But the anecdotes — the impressions our participants shared with us after the experiment — were fascinating. One said: ‘I know this is my favorite song but it doesn’t feel like it usually does.’ Another: ‘It sounds pretty, but it’s not doing anything for me.’ ”

    Photo by Eric Nopanen via Unsplash

    Although the neural underpinnings of music cognition have been widely studied in the last 15 years, the study found relatively little is known about the neurochemical processes underlying musical pleasure. Preliminary studies have shown both performing and listening to music modulate levels of serotonin, epinepherine, dopamine, oxytocin, and prolactin. Music can reliably induce feelings of pleasure, and indeed, people consistently rank music as among the top ten things in their lives bring pleasure, above money, food and art. 

    RELATED: Most Marijuana Users Smoke To Unwind While Listening To Rock Music

    Aside from the strong findings, the study also suggests musical therapy may be much more effective than previously known. And musical therapy is not a “new-wave” form of treatment for improving mental health. It is one of many types of therapy.

    According to the American Music Therapy Association:

    “The idea of music as a healing influence which could affect health and behavior is as least as old as the writings of Aristotle and Plato. The 20th century discipline began after World War I and World War II when community musicians of all types, both amateur and professional, went to Veterans hospitals around the country to play for the thousands of veterans suffering both physical and emotional trauma from the wars.

    marijuana in music
    Photo by Kelly Sikkema via Unsplash

    “The patients’ notable physical and emotional responses to music led the doctors and nurses to request the hiring of musicians by the hospitals. It was soon evident that the hospital musicians needed some prior training before entering the facility and so the demand grew for a college curriculum. The first music therapy degree program in the world, founded at Michigan State University in 1944, celebrated its 50th anniversary in 1994. The American Music Therapy Association was founded in 1998 as a union of the National Association for Music Therapy and the American Association for Music therapy.”

    RELATED: The Day Bob Dylan Turned The Beatles On To Weed

    The McGill University study proved to be “the most involved, difficult and Sisyphean task our lab has undertaken in 20 years of research,” according to Levitin. “Anytime you give prescription drugs to college students who don’t need them for health reasons, you have to be very careful to ensure against any possible ill effects.”

    Music’s universality and its ability to deeply affect emotions suggest an evolutionary origin, and these recent findings “add to the growing body of evidence for the evolutionary biological substrates of music,” the researchers write.

    Amy Hansen

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  • Can Gravity Make People Sick?

    Can Gravity Make People Sick?

    Bad things happen to a human body in zero gravity. Just look at what happens to astronauts who spend time in orbit: Bones disintegrate. Muscles weaken. So does immunity. “When you go up into space,” says Saïd Mekari, who studies exercise physiology at the University of Sherbrooke, in Canada, “it’s an accelerated model of aging.” Earthbound experiments mimicking weightlessness have revealed similar effects. In the 1970s, Russian scientists immersed volunteers in bathtubs covered in a large sheet of waterproof fabric, enabling them to float without being wet. In some of these studies, which lasted up to 56 days, subjects developed serious heart problems and struggled to control their posture and leg movements.

    Weightlessness hurts us because our bodies are fine-tuned to gravity as we experience it here on Earth. It tugs at us from birth to death, and still our intestines stay firmly coiled in their stack, blood flows upward, and our spine is capable of holding up our head. Unnatural contortions can throw things off: People have died from hanging upside down for too long. But as a general rule, the constant push of g-force on our body is a part of life that we rarely notice.

    Or at least, that’s what scientists have always thought. But there is another possibility: that gravity itself is making some people sick. A new, peer-reviewed theory suggests that the body’s relationship with gravity can go haywire, causing a disorder that has long been a troubling mystery: irritable bowel syndrome.

    This is a rogue idea that is far from widely accepted, though one that at least some experts say can’t be dismissed outright. IBS is a very common ailment, affecting up to an estimated 15 percent of people in the United States, and the symptoms can be brutal. People who have IBS experience abdominal pain and gas, feel bloated, and often have diarrhea, constipation, or both. But no exact cause of IBS has been pinned down. There’s evidence behind many competing theories, such as early-life stress, diet, and even gut infections, but none have emerged as the sole explanation. That is a problem for patients—it’s difficult to treat a condition when you don’t know what to target.

    Brennan Spiegel, a gastroenterologist at Cedars-Sinai Medical Center, in Los Angeles, has a different idea: People with IBS are hypersensitive to gravity as a result of any number of factors—stress, weight gain, a change in the gut microbiome, bad sleep patterns, or another behavior or injury. The idea came to him after watching a relative confined to a nursing-home bed develop classic symptoms of IBS. “We’re upright organisms,” he told me. “We’re not really supposed to be lying flat for that long.” The hypothesis, published late last year in The American Journal of Gastroenterology, is just that, a hypothesis. Spiegel hasn’t conducted any experiments or patient surveys that point to a “mismatch” in our body’s reaction to gravity as the cause of IBS, though the mechanics are all based in firm science. But part of what makes the theory so alluring is that it might encompass all of the other conventional explanations for the disease. “It’s meant to be a new way of thinking about old ideas,” he said.

    So exactly how would someone’s relationship with gravity get off-kilter? Consider serotonin, a chemical that carries messages from the brain to the body. Spiegel sees serotonin as an “anti-gravity substance” because of the role it plays in so many important bodily functions influenced by g-force, such as blood flow. Serotonin can cause blood vessels to narrow, slowing circulation. It can make certain muscles contract or relax. It’s also crucial to digestion, helping with bowel function, getting rid of irritating foods, and regulating how much we eat. Without serotonin, gravity would turn our intestines into a “flaccid sac,” Spiegel writes. Because 95 percent of the body’s serotonin is produced in the gut, if levels spike or plummet from factors such as stress, then the chemical’s possible handling of gravity would be thrown into chaos, affecting digestion. The result, he theorizes, is IBS.

    Other parts of our body that respond to gravity can also be in on the problem. We are hardwired to react negatively to situations in which the pull of gravity might harm us; walk to the edge of a cliff and your body will tell you something. The amygdala in our brain is key to fear responses, and stress of various kinds can cause it to go into overdrive. Spiegel thinks that when stress taxes the amygdala, a person begins overreacting to potential threats, including from gravity. The digestive issues that make up IBS are a manifestation of that overreaction. Sure enough, people with IBS have been shown to have a hyperactive amygdala.

    That is hardly anything close to proof. The thought that this painful and prolonged condition could be a gravity disorder is a major stretch, relying on a renegade interpretation of basic biology. “People just think I’m crazy,” Spiegel said. Many of his fellow doctors are not sold on the idea. The gravity hypothesis is another in a long parade of unconvincing theories about IBS, Emeran Mayer, a gastroenterologist at UCLA, told me. He’s heard them all: “It doesn’t exist; it’s a hysterical trait of neurotic housewives; it’s abnormal electrical activity in the colon.” He added, “I don’t think there’s any other disease that has gone through these peaks of attention-grabbing new theories.”

    Spiegel’s idea has clear holes. If a faulty reaction to gravity triggers IBS, says David C. Kunkel, a gastroenterologist at UC San Diego, then you would expect to see higher rates of IBS among populations living at sea level versus at high altitudes, where g-force is slightly weaker. But that doesn’t seem to be the case: About a quarter of Peruvians live high in the mountains and most Icelanders live at sea level, yet both countries have high rates of IBS. Likewise, IBS rates appear to decrease with age, “which would not be expected if the disease was caused by a constant gravitational force,” Kunkel told me.

    Spiegel is aware that the gravity hypothesis has little support in the field and no proof. But the gravity hypothesis has some logic behind it. The fact that the weightlessness of space travel can drastically change the body lends credence to the idea that other shifts in our relationship to gravity could do the same, says Declan McCole, a biomedical scientist at UC Riverside.

    And the gut may be particularly sensitive to gravity changes. McCole has found that weightlessness made epithelial cells—which line the gut and stop invaders from entering the body—easier to evade. So if our internal chemistry can change in a way that makes us hypersensitive to gravity, then, to McCole, it stands to reason that such a shift could hit the gut hard. He’s less sure of whether that hypersensitivity exists. If it does, then why haven’t we identified any chemicals that help handle gravity, as we have for fear or sex drive or hunger? That molecule may indeed turn out to be serotonin, but right now there’s no proof.

    The gravity hypothesis really matters only if it is meaningful for people with IBS. And that’s not guaranteed. Tying the very real pain of IBS to such a fantastical idea may seem closer to mythology than medicine, leaving patients feeling dismissed or belittled. Or they may throw up their hands in despair and prepare for a lifetime of pain: If the immovable force of gravity is the enemy, then why bother fighting?

    But if there is some truth to it, then the hypothesis could also provide a possible starting place for treatments. Some of Spiegel’s suggestions are already common, such as weight loss and medications that decrease serotonin, but he also advocates for some gravity-specific therapies. “I do talk about it with my patients,” Spiegel said. “I recommend certain yoga poses; I recommend tilt tables.” People who have IBS may balk at his more radical ideas, such as moving to a higher altitude or farther from the equator.

    The gravity hypothesis may never be anything more than a hypothesis. We have a long way to go before truly knowing whether the human body can develop a hypersensitivity to gravity that can make us ill, or whether some of us are better equipped to handle gravity than others. But the weight of evidence is enough to make us think twice before ignoring the idea that our body’s relationship to gravity can go awry—including for those of us not coping with IBS. If gravity might contribute to IBS, why not other ailments too? And then, why can’t it also be harnessed for good? Mekari and his colleagues recently found that lying at a six-degree downward angle sped up response times to cognition tests—pointing to a possible link between gravity and executive functioning. Antigravity treadmills, which help astronauts prepare for weightlessness, are being studied for the treatment of cerebral palsy, Parkinson’s disease, and sports injuries.

    All of these unknowns about gravity can feel haunting. Life on Earth has changed a lot since its first forms appeared about 4 billion years ago, but through it all, gravity has seemingly remained constant—perhaps the single thing that connects every organism that has ever lived. What if there’s still much we have to learn about what it’s doing to us? After all, right now your body is coping with gravity, just as it has been for every other second of your life. Perhaps it would be weirder if gravity wasn’t doing anything to us over time. “Every fiber in our body is straining to manage this force,” Spiegel said. You don’t need to spend 56 days in a bathtub to figure that out.

    Jessica Wapner

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