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Exposure to Morning Sunlight Profoundly Affects Mood, Health, and Nighttime Sleep


I didn’t pay attention much when my midwife first suggested to try and get our kids outside before noon in order to help them sleep at night. I’d never heard anything like that before - and it also seemed counterintuitive. When March rolled around this year, we were looking for simple strategies to help improve the health of our family and that search took me back down the road toward this concept of morning sunlight exposure. Since first being introduced to the idea I’d read a little bit more about it but we had never committed to it before. Most often, our outside time was in the afternoon - after lunch, schoolwork and chores. With life flipped upside down, we gave morning sunlight exposure a go and the results were immediate and they were remarkable. So much so that we put out a month long “Sunlight Before Noon” challenge that many of you participated in. As we head into the holiday season and into the short winter days here in our side of the world we are recommitting to a lifestyle that includes at least 20 to 30 minutes of exposure to morning sunlight and here are a few reasons why:



  1. Exposure to early-morning sunlight helps you sleep at night.

On the surface, it doesn’t seem to make any sense - but it’s true! One human eyeball contains one billion working parts. One billion! The closest most intricate man-made item is a space shuttle, with five hundred million working parts. One of your eyes is twice as complex as the most complex thing man has ever made. According to Jacob Liberman, OD, Ph.D., when sunlight enters the eyes, the entire brain lights up. Indoor light is solely for vision, but full spectrum sunlight affects so much more. Light is a guide for the trillions of cells in our body through a process called “photobiomodulation”. Light entering the eyes transmits time-of-day information to the brain and to the body. Sunlight sends a “wakeup” signal to the pituitary gland and the pituitary gland response by releasing hormones. Bright morning light tells your body to suppress melatonin production and increase cortisol production (which is good for you in healthy amounts) and serotonin. Eventually, the pineal gland metabolizes serotonin into melatonin and that’s what helps you naturally fall asleep at night. To summarize, if we expose our eyes, body and face to morning sunlight, our body will respond by increasing serotonin. Serotonin is a precursor to melatonin, the hormone that helps regulate sleep and wake cycles. Morning sunlight provides the raw materials our body needs to make melatonin when the day starts winding down. 2. Exposure to early-morning sunlight enhances your mood. Serotonin is a feel good chemical and one way to control its release is to expose yourself to morning sunlight. There is ample research to suggest that serotonin plays an active role in the treatment of depression. Exposure to full spectrum sunlight in the morning causes our bodies to produce serotonin, which not only helps later on with nighttime sleep, but improves mood throughout the day. Bright lights have been used for a long time as standard treatment for seasonal depression. Outdoor light, even on a cloudy day, delivers considerably more lux than indoor light. Rainy, winter days will produce lux levels of 1000 or more, which is far greater than any inside light will produce - and on sunny, summer days, sunlight can deliver light that is one thousand times brighter than indoor light.


3. Exposure to early-morning sunlight enhances your health. Our bodies are light receptors. Some of the sunlight entering our eyes is sent to the hypothalamus, which “coordinates and regulates most of our life-sustaining functions and also initiates and directs our reactions to stress." (Light: Medicine of the Future by Jacob Liberman, OD, PH.D.) Approximately 100 of our body systems are tied to the day and night cycle. Humans are diurnal creatures, our rhythms revolve around the patters of the sun and the moon. Ivy Cheung, PhD candidate in neuroscience at Northwestern says, “Light is the most important synchronizing agent for the brain on body. Proper synchronization of internal biological rhythms with the earth’s daily rotation has been shown to be essential for health.” 4. Exposure to early-morning sunlight can help with weight loss. According to this study, those with earlier light exposure weighed less - and results can be seen in just three short weeks! “Even after controlling for all non-light exposure factors including food intake, sleep, activity, the influence of morning light on weight was considerable—it accounted for roughly 20% of the subject’s BMIs, meaning those with earlier light exposure weighed less."


For our family, we clearly noticed the effects of outdoor play and sunlight exposure long before we began reading the accompanying research. At this point, however, knowing some of the research helps us stay motivated - especially on cold, wet, dreary winter days when we’d rather stay inside. Knowing these benefits, and assuming there are probably even more that we don’t know, pushes us out and we always notice improvements in health, mood and sleep.

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