When you think of the sun, your first thought might be about the damage it can do. And too much can cause several kinds of serious health issues. But small amounts, especially early in the day before it’s at its brightest, can be good for you in some ways. Do you want to feel happier and healthier? Sunlight exposure offers a natural path to achieving both. This article explores the mood-boosting and weight loss benefits of getting regular doses of sunshine.
The Crucial Role of Sunlight
Sunlight exposure helps your body produce vitamin D. The sun’s UV rays help your body make this nutrient, which is important for your bones, blood cells, and immune system. It also helps you take in and use certain minerals, like calcium and phosphorus. Vitamin D is a nutrient that lifts your spirits and makes you feel good. Likewise, lack of sunlight can make you feel sad or depressed.
How Much Sunlight Do You Need?
This answer is different for everyone. It depends on your skin tone, age, health history, diet, and where you live. In general, scientists think 5 to 15 minutes -- up to 30 if you’re dark-skinned -- is about right to get the most out of it without causing any health problems. You can stay out longer and get the same effect if you use sunscreen. Talk to your doctor about what’s right for you.
The Impact of Sunlight on Weight Management
Morning light also seems to help people keep the fat off. People who had most of their daily exposure to even moderately bright light in the morning had a significantly lower body mass index (BMI) than those who had most of their light exposure later in the day, the study found. and noon to make a difference, but the earlier you get it, the better it seems to work. Scientists think the sun’s rays may shrink fat cells below your skin’s surface. The influence of morning light exposure on body weight was independent of an individual’s physical activity level, caloric intake, sleep timing, age or season. “The earlier this light exposure occurred during the day, the lower individuals’ body mass index,” said co-lead author Kathryn Reid, research associate professor of neurology at Northwestern University Feinberg School of Medicine.
More sunshine means you’re probably getting more exercise too, which is good for you in lots of ways, including shedding pounds. Sunlight can also help you lose weight in several ways:
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- It helps control your appetites and cravings for unhealthy foods.
- It regulates hormones like leptin that control hunger and feeling full.
- It provides vitamin D which boosts your metabolism for burning calories.
- The bright light gives you more energy and motivation to exercise.
Leptin and Ghrelin Regulation
When you get regular sunlight, your whole body functions better. You feel more motivated to be active. Your metabolism runs smoothly. As a result, maintaining a healthy diet and losing weight become more achievable.
Leptin is a key hormone helped by sunlight. It sends signals to your brain that you are full after eating. With leptin working well, you do not overeat or have strong food cravings. Sunlight also reduces levels of ghrelin, the hunger hormone that increases appetite.
Vitamin D and Metabolism
Getting vitamin D is vital too. Most people do not get enough vitamin D. It comes from sunlight exposure on your skin. Vitamin D regulates insulin and boosts your metabolism, the process of burning calories. With enough vitamin D, your body uses energy more efficiently to lose weight.
Sunlight and Mental Well-being
Sunlight helps boost a chemical in your brain called serotonin, and that can give you more energy and help keep you calm, positive, and focused. Doctors sometimes treat seasonal affective disorder (SAD) and other types of depression linked to low levels of serotonin with natural or artificial light. Sunlight's brilliant rays tells our brains to release mood-boosting chemicals like serotonin and endorphins, infusing us with energy and positive emotions. Additionally, it helps regulate our sleep cycles, promoting restorative rest. By basking in the sun's radiance, we unlock heightened vitality and well-being.
People with seasonal affective disorder especially benefit from sunlight and vitamin D supplementation (when sunlight is inadequate). This is when your mood drops during darker winter months. Getting daily sunlight helps relieve sadness and lack of motivation from this disorder.
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Sunlight and Your Body Clock
Your eyes need light to help set your body’s internal clock. Early morning sunlight in particular seems to help people get to sleep at night. This may be more important as you age because your eyes are less able to take in light, and you’re more likely to have problems going to sleep. “Light is the most potent agent to synchronize your internal body clock that regulates circadian rhythms, which in turn also regulate energy balance,” said study senior author Phyllis C. Zee, M.D. Zee is the Benjamin and Virginia T. Boshes Professor of Neurology and director of the Northwestern Medicine Sleep and Circadian Rhythms Research Program at Northwestern University Feinberg School of Medicine. “If a person doesn’t get sufficient light at the appropriate time of day, it could de-synchronize your internal body clock, which is known to alter metabolism and can lead to weight gain,” Zee said.
The Impact of Blue Light
A new study - by researchers at the University of Alberta in Edmonton, Canada - reveals an unexpected culprit for winter weight gain: the absence of sunlight. The researchers, who were led by the auspiciously named Peter Light - from the Alberta Diabetes Institute - examined the effect of sunlight on subcutaneous fat cells, or white fat cells that can be found right beneath our skin. Light and team examined the so-called subcutaneous white adipose tissue (scWAT), which, as the authors explain, is the “major fat depot in humans and a central player in regulating whole body metabolism.”
Accidentally, they discovered that scWAT cells tend to shrink under the effect of the sun’s so-called blue light - that is, the visible type of light that boosts attention and mood during the day.
To further test their discovery, the scientists took samples of scWAT from patients undergoing weight loss surgery and examined the effect of the sun’s blue light on the fat cells.This is what they found: “When the sun’s blue light wavelengths - the light we can see with our eye - penetrate our skin and reach the fat cells just beneath, lipid droplets reduce in size and are released out of the cell.
Balancing Sun Exposure and Safety
Too much time outside can raise your chances of skin cancer, but the risk of developing certain conditions such as multiple sclerosis and other autoimmune diseases may be higher in people who live in northern climates. Scientists think this might be linked to lower levels of vitamin D. Researchers think the three primary types of skin cancer -- melanoma, basal cell carcinoma, and squamous cell carcinoma -- are mostly caused by too much time in the sun. So it’s very important to use sunscreen or cover up if you’re going to be outside longer than 15 minutes or so. But regular, small amounts of ultraviolet light may help ease the symptoms of certain skin conditions like eczema, psoriasis, and vitiligo. Too much time outside without protection can not only make you more likely to get skin cancer, it can make your skin age faster, too, causing wrinkles, a leathery texture, and dark spots. And sunburned skin uses white blood cells from your immune system to heal. That can affect your body’s ability to fight off germs and make you more likely to get sick.
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Protective Measures
You need sunglasses that block UV light and broad-brimmed hats whenever you’re outside for a while. The sun can damage your eyes any time, not just in summer, and the rays can pass right through clouds. (Don’t forget that kids need this same protection, too.)
An SPF of 30 or higher is best. Look for “broad exposure,” which blocks more of the UV light. Put it on 30 minutes before you go outside, and don’t forget areas like your lips, ears, and neck. Put more on if you swim or sweat. If you do it before age 35, you’re 60% more likely to get melanoma, the most serious form. Even one session can raise your odds of melanoma by 20% and other types by as much as 65%. If you want that all-over body tan, tanning lotions might be an option. Most are safe, but they usually don’t have sunscreen in them, so don’t forget to put that on as well.
Check your skin once a month or so. If possible, ask a family member to help if you can’t see everywhere on your body. Stand in front of a full-length mirror -- a chair and a hand mirror can help -- and look all over for any new growths or changes in old spots.
Maximizing Benefits Safely
To get the mood and weight loss benefits, try to get sunlight exposure every day. Experts recommend 10-15 minutes of midday sunlight if possible. Sit by a window if you can't go outside.
The best sun exposure times are between 10 AM - 2 PM. This is when the sunlight provides the most vitamin D. Morning sunlight also helps set your sleep cycle. Just 10-30 minutes per day of direct sun can make a big difference.
Be safe in the sun too. Use sunscreen if outside for over 15 minutes. This prevents burns and skin damage. A little unprotected sun exposure is healthy, but too much is harmful. So get your daily dose of sunshine, then cover up.
The Broader Impact of Sunlight on Health
For thousands of years humans have understood that sunlight has an important and significant impact on human health and disease. Sunlight may be beneficial for the treatment of a number of medical conditions including some cancers and neurodegenerative diseases. Chronic but not acute exposure to UVR was associated with significantly reduced incidence of cancers of the breast, prostate, colon/rectum and non-Hodgkin’s lymphoma. Cancer survival is associated with better responses in patients that have higher cumulative sun exposure or who are diagnosed in summer/autumn, which was attributed to the activity of increased circulating 25-hydroxyvitamin D. Sun exposure is inversely associated with some (but not all) infections, including tuberculosis and acute respiratory tract infections.
Increased sun or UVR exposure is associated with reduced development and/or severity of immune-driven diseases including autoimmune diseases such as arthritis, inflammatory bowel disease, multiple sclerosis, and allergic conditions such as asthma and anaphylaxis. The evidence around the protective effects of sun exposure in affecting multiple sclerosis is particularly strong, where increased sun exposure (and serum 25(OH)D) was associated with reduced risk of multiple sclerosis, particularly in childhood and adolescence.
Understanding UV Radiation
The wavelengths of UVR are further divided into three main categories: UVA (315-400 nm) and UVB (280-315 nm), which, respectively, comprise 95% and 5% of UV rays that reach the Earth’s surface; and, UVC (100-280 nm), which is prevented from reaching the Earth’s surface by the ozone layer. UVA can penetrate much deeper into the epidermis than UVB with <10% of UVB reaching the basal germinal layer compared to >20% of UVA. The amount of solar UVR that reaches the terrestrial surface at any given place and time is influenced by a variety of factors including; time of day, season, geographic latitude, altitude, cloud cover and surface type.
Negative Effects of UVR
The negative health effects of exposure to UVR have been closely examined. These include sunburn and increased risk of skin cancers (melanoma, lip cancer, and keratinocyte cancers) and ocular diseases (cataracts, pterygium, ultraviolet keratitis and conjunctival neoplasm). Excessive skin exposure can cause skin erythema (reddening of skin), with oedema and tissue inflammation. The total amount of exposure to UVR and excessive exposure resulting in sunburn in childhood and adolescence significantly increases an individual’s risk of developing melanoma.
Sub-erythemal (non-burning) doses of UVR also have biological effects. Absorption of UVR by epidermal cells in skin and the eye leads to the production of reactive oxygen and nitrogen species which can damage biomolecules such as membrane lipids and deoxyribonucleic acid (DNA). UVR (both UVA and UVB wavelengths) directly damages DNA through the formation of pyrimidine dimers. These are the predominant DNA lesions in human skin exposed to UVR.
UVR can promote tumour growth through immunosuppression. As far as the ability to cause genetic mutation and suppress human immune responses is concerned, at an equal dose, UVB is far more potent (and carcinogenic) than UVA radiation. However, humans are exposed to more UVA than UVB as the relative amounts of UVA (95% of UVR) in sunlight far exceed UVB (5% of UVR). The ability of UVR to cause genomic damage may be an initiating factor in the pathogenesis of skin cancers with a role for reactive oxygen species in UVR-induced eye disease.
Exposure to UVA radiation still occurs when the UV index (UVB-weighed) is low (for example in winter in temperature climates, or early morning and late afternoon), or through window glass (which blocks UVB radiation). UVA poses risks to human health because of its capacity to induce pro-inflammatory cytokine production in skin and degrades vitamin D in skin; however, UVA may induce the release of nitric oxide from stores in skin to improve blood pressure.