The sun rises earlier in March, and the outside temperature will, hopefully, gradually become more pleasant. We long to be free from our tiredness and cold feet. Why does our body have such difficulty with winter? Winter has two striking characteristics: it is cold, and dark. We don’t always feel very fit in the winter. But most of us survive it every year. Are we just pretending, with our dullness and sore toes? Or will winter really not bother us? It may be true that some people feel less fit in the winter. Many people see too little daylight in winter. Until 150 years ago, we had little trouble with a lack of light. We were outside a lot during the day. But since the industrial revolution (from the end of the eighteenth century) we have been indoors more and more. Children go to school, and people work in the office all day. We see less and less real daylight, especially in winter.
Lack of light disrupts
The rhythm of light and dark regulates many processes in our body. Every 24 hours it is very light exactly once (during the day) and very dark exactly once (at night). This 24-hour rhythm controls your sleep-wake rhythm. A lack of daylight can significantly disrupt the rhythm. Normally our sleep-wake rhythm runs exactly right, even in winter. Our internal biological clock closely monitors the 24-hour rhythm. It regulates the release of hormones at the right time, making us sleepy or awake. Although no one has a biological clock with a rhythm of exactly 24 hours, as long as we see enough daylight, no problems arise. This is because our clock resets itself every day to the 24-hour rhythm. It appears that morning light between nine and eleven o’clock plays a key role in equalization. In the absence of morning light, adjustments in winter sometimes go wrong. If no daylight reaches your eyes at all, your clock will run further and further out of rhythm. This can happen to people who come to work in the dark, stay indoors all day and return home in the dark. For example, for someone with a biological clock of 24.5 hours, after 24 days without daylight, the biological clock is disturbed by twelve hours. Result: you are tired during the day, and wide awake at night. One consolation, after another 24 days in the dark, the clock will run smoothly again and you will feel good about yourself again. A disrupted internal clock can explain why many people regularly feel uncomfortable in the winter.
Put yourself in the light
If your biological clock gets upset during the dark months, you can do something about it. Go outside as much as possible and make sure you get light, especially in the morning. Make sure you sit no more than two or three meters from the window so that you get enough daylight in your eyes. There is little point in replacing your 40-watt bulb at home with a 60-watt one. But halogen lighting can help time your clock. A 200 or 300 watt bulb should work. Only use it when you need it. So don’t sit under such a lamp in the evening, because then you will be awake all night.
The culprit is short days
This form of light therapy is not sufficient for real winter depression. People with real winter depression have a great need for sleep. After a twelve hour night they are still tired. They also need food much more, and can gain a lot of weight in the winter. In the spring the kilos will fly off.
The complaints begin in autumn and winter, when the mercury drops and the days become shorter. In areas with the same day length but different temperatures, people suffer equally from the condition. Temperature is therefore not a cause. The more you go to the poles, the more people have winter depression. In Alaska, ten in a hundred people have the disease, in the Netherlands three in a hundred. Since temperature plays no role, the short days are the culprit.
Therapy replaces sun
If there is a lack of light, light therapy should help. Research into winter depression shows that seventy to eighty percent of patients feel better after a week. Going to the sunbed for a while doesn’t help. Tanning bed light contains ultraviolet radiation. If you get that in your eyes, you’ll go blind. The light of the therapy should hit your eyes. It is imitated daylight, without harmful ultraviolet radiation. The intensity of 10,000 lux is comparable to the light intensity of 45 minutes after sunrise, much stronger than that of a normal lamp.
The healing effect of light therapy is still largely a mystery, but it is clear that it works. It is still unclear why most people become depressed due to a lack of light. According to researchers, no indications have yet been found that show that winter depression, just like a disrupted sleep-wake rhythm, is caused by a disrupted 24-hour clock. In America they think so, but there are different clocks, those for the daily rhythm and those for the annual rhythm. It seems that something is wrong with the annual clock of a winter depression patient.
Brain regulates heat
Besides being dark, it can also be quite cold in winter. Some people can handle this better than others. Your own thermostat in your brain ensures that you stay at a temperature of 37 degrees Celsius. If your body cools down, the heat controller adjusts the temperature. Your body has two reactions to cold. Your body produces more heat and wants to lose less heat.
Organs and muscles constantly produce heat. Your resting metabolism produces a heat output of 90 to 100 watts, just as much as a large light bulb. A trained athlete who exerts maximum effort can even reach 1000 watts. In the cold your heat regulator screws up. And you start shivering. Your body does this to prevent hypothermia. The brain receives a message from your thermostat that it is getting too cold and sends a signal to the muscles to shiver. A healthy trained person produces four times more heat than normal with this muscle movement. Behavior also plays a major role. When we are cold, we move more. We walk or pace, and we put on warm clothes.
During exercise or in the summer, when you are hot, the veins in your skin and hands often thicken. Your body widens the blood vessels, which causes you to lose more heat and cool down. If you are in the cold, it works exactly the other way around. The veins in your skin narrow, blood flow decreases, and you lose less heat. Normally this temperature regulation is very gradual. In people who have chilblains or chilblains, the vessels in the skin react abnormally to cold. The barrels close way too far. Your toes don’t get enough blood. They turn white and hurt. When you are in the heat again, the skin vessels suddenly open, but much too much. That tingles, and you get red, swollen toes. Chilblains can be so severe that you develop blisters and holes in your skin. It is impossible to eliminate the cause of this, but you can prevent the symptoms. Make sure your whole body stays warm and your blood does not cool down. Putting on thick socks while wearing paper-thin pants does not help.
Wind carries heat
In the Netherlands we do not have arctic temperatures, but frostbite and skin injuries do occur here. People who work outside, vagrants or people who work with water suffer from it. And it’s not just in winter that we run the risk of being overwhelmed by the cold. Relatively many cases of hypothermia occur in the summer because many people spend their free time on and in the water. If you emit more heat than you produce for a long period of time, your thermostat can no longer keep up and you will eventually become hypothermic. This already occurs when the temperature around the heart and brain falls below 35 degrees Celsius. It is very difficult to say exactly how long you have to walk, swim or cycle in a certain temperature to become hypothermic. There is no threshold for a temperature or time. There are all kinds of factors that play a role, such as fat percentage, physical condition and nutrition.
In any case, it does not have to be freezing to become hypothermic or suffer cold injuries. You can also get quite chilled in the rain and wind. The passing wind easily takes your heat away, and then your body cools down quickly. Rain is even more treacherous. Water absorbs heat much faster than air. You are more likely to become hypothermic in the rain.
Cold makes you hard
People who have been living in the cold for a long time or working in the cold for a long time, such as Eskimos and fish fillers, appear to be able to adapt to the conditions. They are better armed against the extremes. Eskimos have short, thick fingers and therefore lose less heat. The fingers of fish filleters have better blood circulation. Cold injuries are less likely to occur, allowing them to use their fingers better. The disadvantage of this is that they lose more heat and are in principle more likely to suffer from hypothermia. So the adjustment of their body only helps a little. It is mainly ‘hardening’ that makes these people better able to withstand the cold.
Not everyone is happy when winter is over. For people with a light allergy, the problems start when the sun shines more. 10 to 20 percent of Europeans suffer from this. In the spring or during sun holidays, you get itching, blisters or other rashes as soon as you come into the sun. A nice sun during winter sports can also be too bright. It usually helps to get your skin used to the sun in the spring. The skin becomes thicker and more pigment is produced. This protects against ultraviolet radiation. You will then get a less likely or less serious rash in the summer. That does not mean that people with dark skin do not suffer from it. They can also be hypersensitive to the sun, although the chance of this is smaller.