Winter is coming on fast. Now the clocks have gone back, and it is noticeably darker. The lack of light during the winter months considerably affects our body chemistry. Last week, I wrote about vitamin D, which is made in the skin under the influence of sunlight. But light has even further reaching effects on our body chemistry.
A considerable number of people feel blue during the winter months. Everything seems like an effort, we lose interest in doing things we normally enjoy, can’t seem to motivate ourselves to exercise or go out and meet with our friends, and many suffer from downright depression, which only lifts once spring comes and the days are getting longer again. This common condition is called “Seasonal Affective Disorder” (SAD), often referred to as “the winter blues”.
It affects women more often than men, and particularly people who are on the verge of depression already. The lack of the neurotransmitter serotonin due to low levels of light can tip sensitive people over the edge. Serotonin is a brain chemical required to make us feel happy and content, for motivation and activity. Many common anti-depressants work by increasing serotonin levels in the brain. While serotonin production requires light, a closely related neurotransmitter – melatonin – requires darkness. Melatonin is made from serotonin. During the dark months of winter, more serotonin is converted into melatonin, further reducing the levels of our “happy” neurotransmitter. Melatonin is required for sleep, but too much of it may make us sleepy during the day, and in fact fatigue is a common symptom of SAD. Remember that low vitamin D levels also affect mood. No wonder then, that many of us are feeling low during winter.
A promising way to counteract SAD is the use full-spectrum light, either from a lightbox or light bulbs in the house. Sufferers of SAD respond well to full-spectrum light, about 70% report considerable improvement. For this beneficial effect, it is necessary to spend 30 minutes each day in front of a full-spectrum lightbox or six hours with artificial full-spectrum lighting in the house. 98% of light enters our body through the eyes, only 2% through the skin. Looking out of a window doesn’t help, as glass blocks the ultraviolet light. Sunglasses won’t give you full-spectrum light either, so if you can, leave them off when you are out during the winter and the sun is not directly in your face.
Diet, too, can help coping with SAD, though not as efficiently as light treatment and exercise. The amino acid tryptophan is a precursor for serotonin. It is one of the eight essential amino acids – ie we have to ingest it, the body cannot make it –, and it is found in a variety of foods: dairy products, eggs, red meat, poultry, fish, chocolate, oats, dried dates, chickpeas, almonds, sunflower and pumpkin seeds, bananas, spirulina and peanuts all contain tryptophan. Although turkey is often referred to as an excellent source of tryptophan, it has no more of the amino acid than other poultry meats. Unfortunately, it is very difficult for tryptophan to access the brain, but transport can be enhanced by combining tryptophan-rich foods with complex carbohydrates such as brown rice, brown pasta, wholegrain bread or oats.
One of the best ways to combat SAD, however, is exercise, particularly exercise outdoors. Exercise has been found to be effective in combating depression. When your body feels better, so does the mind. It doesn’t really matter what you do as long as you are active. If you don’t enjoy exercise, don’t worry: Even a 10-minute walk during your lunch break, getting off one bus stop early, walking to the shops instead of driving, taking the stairs instead of the escalators or lift is effective. Try and incorporate small changes like these and you may soon find that you are able to do more, walk further, or climb faster, which is a great incentive to keep going. As most light accesses the body through the eyes, it would be great if – despite the weather – you could exercise outdoors to give your body the chance to soak up some light.