How Natural Light Recharges Your Health

by Christiane Northrup, M.D.


No matter where you live in the Northern Hemisphere, if it’s October you can’t help but notice that daylight is disappearing! If you live in Maine like I do, this is particularly apparent. Invariably, I find myself trying to “bank” sunlight whenever I can, in an attempt to store up for the winter. This isn’t surprising! Natural light is a nutrient, and the amount of daylight your body is exposed to can influence your moods, energy level, and your overall health.

There’s no question that during the week after we set our clocks back, I feel like staying in bed longer and also feel drawn to high-carb comfort foods, especially chocolate brownies or garlic mashed potatoes. (Eating carbs increases serotonin, a “feel-good chemical,” which you might find in short supply if you’re not getting enough natural light). Some people also experience more muscle and joint soreness as the daylight hours wane. When you add these physical changes to the stress of the holidays, you have a physiological set up for the seasonal blues.

What can you do about this seasonal sluggishness and malaise? Let me explain how a little more daylight can charge up your body and brain with more energy, fewer aches and pains, and better sleep.

Slugging away

naturalLight-1239175591So what makes us so sleepy in winter? Our circadian rhythms, those that govern our sleep and wake cycle, are different from season to season. During the winter, we also tend to make more melatonin—a naturally occurring chemical in the brain that causes sleepiness. Research has shown that these two factors, which favor decreased activity and hibernation, are directly related to the amount of full spectrum light our eyes take in.

When you go outside on a sunny day, your eyes are exposed to natural light (daylight), the original full spectrum light. Although your eyes don’t perceive it, natural light contains all the colors of the rainbow (which is where the name full spectrum comes from). You also get some ultraviolet A and B (UVA, UVB) light. Typical indoor lighting contains mostly yellow and orange light waves and fewer green, blue, and purple waves. In other words, it’s artificial light. And your body knows it!

On the other hand, when you expose yourself to full spectrum lighting, chances are good that you will find it refreshing. And you will feel some relief from sleepiness and even premenstrual moodiness or irritability. All you need to do is expose yourself to regular doses of full spectrum light generated ambiently by a light box and/or full spectrum light bulbs. (Although light is absorbed by the eyes, you should never stare at a light box or light bulb because it can cause eyestrain, headaches, and other symptoms. Simply sit somewhere where the light reaches you out of the corner of your eye.) Light boxes can be used during the day on a cloudy day, in the late afternoon, or early morning or evening to extend the day.

I use full spectrum light bulbs throughout my house and office year-round. I also turn on a light box in my family room in the evening during fall and winter. Not only does this give me additional exposure to a health-enhancing light source after dark, I find natural light much easier to work and read by. I’ll bet you’ve noticed that it’s easy to read a menu without glasses when you’re sitting outside, but reading this same menu in a dimly lit restaurant is nearly impossible! That’s because your eyes work optimally in natural light, but not in the artificial kind. Most full spectrum light bulbs are the compact fluorescent type that are energy efficient, and that benefits the environment as well.

There are numerous studies that have demonstrated the connection between full spectrum light and serotonin levels. Willeit1 Interestingly, a drop in melatonin enhances “feel good” hormones, including endorphins and serotonin, which help you feel both alert and calm. This transformation occurs in the brain as a result of being in more light. That’s why getting outside at noon for a half hour walk on a sunny day during the winter months will lift your mood greatly. Hold the sunglasses whenever possible. They block some of the colors of the light waves.

Skin Deep

Did you ever wonder why you long to sit in the sun on a tropical island in the dead of winter? That’s because light affects the body in a positive way when the skin is exposed to sunlight, too. The UVB rays cause vitamin D to be produced, and vitamin D is a hormone that initiates a chain reaction that literally enhances the health of every cell in your body. Recent studies show that this may chase away the flu, rid you of your winter blues, and reduce musculoskeletal pain that you experience in the winter. Here’s a summary of some recent studies:

  • World renowned vitamin D researchers John J. Cannell, M.D., and Michael Hollick, M.D., believe that flu rates rise in the winter in northern latitudes because people’s vitamin D levels drop in the winter. Cannell2 Their research indicates that among other things, adequate blood levels of vitamin D along with regular consumption of food and/or supplements that contain vitamin D3 is a safe way to enhance the immune system. As kids, my dad insisted we take cod liver oil all winter long—turns out he was way ahead of his time.
  • Researchers in Australia reported a marked improvement in subjects in a double blind study whose moods were affected seasonally. Lansdowne3 This occurred in patients receiving both 400 IU and 800 IU of cholecalciferol (vitamin D3). (Vitamin D3 is available by prescription only. It’s far more potent than the vitamin D2 that’s found in fish oil and other vitamin D supplements.) But you don’t need studies to tell you something that you know innately! Sitting in the sun feels good. And it leads to a general sense of well-being.
  • Recently a number of studies have shown that low vitamin D levels contribute to musculoskeletal pain. Plotnikoff4 (And people who continually experience pain are more likely to be depressed, especially during the fall and winter.) This is true of pain of all kinds, and may give doctors new insights into pain management for people with low levels of vitamin D.##hooten## This finding is significant because patients with low vitamin D levels don’t respond as well to traditional pain management treatments (like pain killers).##american## So something that feels as wonderful as sitting in the warm sun can increase vitamin D levels, which in turns strengthens bones and muscles while eliminating pain. Isn’t Mother Nature remarkable?

Let the Sun Shine In

Vitamin D is the sunshine vitamin. So let it in whatever way you can this winter. For you that might mean a trip to a sunny spot. If that’s not in the cards then consider visiting a tanning booth in your neighborhood that has beds with UVB light for ten minutes at least once per week. Twice would be better. (Don’t get a burn!) Some safe sun exposure along with a regular daily dose of vitamin D (1,000–1,200 mg a day) will do wonders for your health all year long and chase away those winter symptoms before you know it.

I’d also suggest that you get your vitamin D blood levels checked. Your level should be above 30 ng and optimally it will be 45 ng or higher. If your level is lower than that, ask your practitioner to prescribe a high potency vitamin D until your levels are normal. Then sun exposure and regular intake of vitamin D will keep your levels normal. (By the way, wild Alaskan sockeye salmon is loaded with vitamin D, and 3.5 ounces contains over 600 IU of vitamin D!)

During the months when natural light dims, your spirits don’t have to go with it. Bring the sunshine inside wherever you are. A good light box is a wonderful investment for your health and your mood. My business manager and I get ours out every fall and make sure we spend a couple hours working in the natural light it produces. Oh, one more thing: when the natural light dims outside, it’s a sign to go inward to find the light within yourself. It’s quite natural for any dark emotions from unfinished business to come up now. Your job is to shed light on them—both through your consciousness and through natural full spectrum light.


  1. Willeit, M., 2007. Enhanced serotonin transporter function during depression in seasonal affective disorder, Neuropsychopharmacology, Sep 19.
  2. Cannell, J.J., Hollis, B.W. 2008. Use of vitamin D in clinical practice, Altern Med Rev, Mar;13(1):6-20.
  3. Lansdowne, A.T., Provost, S.C., 1998. Vitamin D3 enhances mood in healthy subjects during winter, Psychopharmacology (Berl). 1998 Feb;135(4):319-23.
  4. Plotnikoff, G. 2003. Prevalence of severe hypovitaminosis D in patients with persistent, nonspecific musculoskeletal pain, Mayo Clinic Proceedings, December; vol. 78: pp. 1463-1470.
  5. Hooten, W.M., Turner, M.K., and Schmidt, J.E., 2007. Prevalence and clinical correlates of vitamin d inadequancy among patients with chronic pain, Presentation A1380, October 15.
Last Updated: October 1, 2008

Christiane Northrup, M.D.

Christiane Northrup, M.D.

Christiane Northrup, M.D., is a visionary pioneer and a leading authority in the field of women’s health and wellness. Recognizing the unity of body, mind, and spirit, she empowers women to trust their inner wisdom, their connection with Source, and their ability to truly flourish.

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