What have randomized controlled trials of light therapy—bright morning light—found for weight loss?
If the weakening of our circadian rhythm can cause weight gain, can strengthening it facilitate weight loss? You may remember the swing ratio of child I shared previously. Regular morning meals can I give our cycles are a small daily boost, but the biggest boost comes from our exposure to bright morning light. Likewise, exposure to light at night could is analogous to the evening meal as you can see below and at 0:31 in my video Shedding Light on Shedding Weight.
Of course, we had candles to illuminate our nights for 5,000 years, but the flames from candles, bonfires, and oil lamps “turn strongly toward the red edge of [light] spectrum; As a result, firelight has much less effect on circadian rhythmicity than electric light.” It is the shorter blue wavelengths that specifically regulate our circadian clocks. Electric lighting, which we only have he had for just over a century, “has gradually changed since the 1960s from a form of incandescent light consisting primarily of low-level yellow wavelengths to high-intensity discharge forms,” such as fluorescent and LED lamps, “containing blue wavelengths” , which is more similar to morning sunlight and have the strongest effect on our circadian rhythm.
Use wrist cash to Count exposure to ambient light, the researchers found that increased exposure to light in the evening and at night was associated with a subsequent increased risk of developing obesity over time. This was supposed to be due to circadian misalignment, but could it be a sign of not getting as much sleep and maybe that’s the real reason people gain weight? That’s it controlled in a study of more than 100,000 women, which found that the odds of obesity tended to increase with higher light exposure at night, regardless of sleep duration.
Compared to women who reported that their bedrooms at night were either too dark to see their hand in front of their face or at least dark enough that they could not see across the room, those who reported that their bedrooms were bright enough to see across the room. were significantly heavier. Not everyone slept with the night lights on. Without blackout curtains on the windows, many neighborhoods can is bright enough to cause circadian disruption. Using satellite imagery, scientists were even able to correlate higher obesity rates with brighter communities. There’s so much light at night these days that, short of blackout, the only Milky Way our kids are likely to see is inside a candy wrapper.
Although the amount of sleep could be controlled, what about sleep quality? Maybe people who sleep in bedrooms that aren’t as dim don’t sleep as soundly, resulting in them being too tired to exercise the next day, for example. You can’t know for sure whether nighttime light exposure is harmful in itself until you try it. When this was done, these randomized for exposure to bright light for a few hours in the evening or exposed if only for one night he suffered adverse metabolic consequences.
The most interesting question then becomes: Can circadian synchronization with morning bright light therapy be a viable weight loss strategy? Insufficient morning light may be the circadian equivalent of skipping breakfast. Interior lighting is very bright at night, but can be too dim during the day to strongly stimulate our daily rhythm. Light exposure from Damn it outdoors in the morning, even on a cloudy day, is associated with lower body weight compared to typical office lighting, so some doctors have started tries “phototherapy” to treat obesity. The first case reports began to be published in the 1990s. Three out of four women lost an average of about four kilograms in six weeks of morning exposure to bright light, but there was no control group to confirm the effect.
Ten years later, the first randomized controlled trial was conducted published. Overweight subjects were randomized to an exercise intervention with or without one hour per day of bright morning light. Compared to normal indoor lighting, the bright light group lost more body fat, but it’s possible the light simply motivated them to exercise harder. Studies show that exposure to bright light, even the day before exercise, can enhance performance. In a handgrip endurance test, exposure to hours of bright light Increased the number of contractions to exhaustion from about 770 to 860 the next day. While light-induced improvements in activity or mood may be helpful in their own right, it will be years later before even I found out whether light exposure itself could enhance weight loss.
Following an unpublished study in Norway that purported to show a 12-kilogram weight loss advantage over eight weeks of 30 minutes of daylight (compared to indoor lighting), researchers tested three weeks of 45-minute vigorous breakfasts compared to the same hour of sitting in front of an “ion generator” that appeared to be on but stealthily turned off. As you can see in the chart below and at 5:08 in mine videothe three weeks of light Rhythm apart from the placebo, but the average difference in body fat reduction was only about a kilogram. This light advantage did not seem to correlate with mood changes, but bright light itself might stimulation serotonin production in the human brain and cause the release of adrenaline-like hormones, both of which could benefit body fat in addition to any circadian effects.
Regardless of the mechanism, bright morning exposure to daylight could present a new weight loss strategy straight out of the blue.
I have a whole series on chronobiology. You can see all the videos at topic page. The latter are listed below in the related posts and help give 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 on related posts below or browse all of my weight loss videos here.
