Crappy pop songs aside, most people will tend to describe a bright, clear day as “happy” and an overcast, drizzly one as sad. Words such as “gloomy”, “blustery”, “calm” and “dry” can be used to describe either the weather or a person’s emotional makeup and it’s not all that difficult to spot the parallels between the two usages.
Our environment does have an effect in the way we feel, and while the sky outside is not something we normally pay that much attention to, it has a profound effect on our mental state, nor is this a case of external symbols affecting our internal reality (although that might play a role too). The mechanisms involved are often physical in nature.
Seasonal Affective Disorder
Appropriately abbreviated as SAD, Seasonal Affective Disorder is characterized by increased moodiness, reduced energy levels, and depression during the autumn and winter months. The higher the altitude, the shorter the daylight hours in winter days and the greater the prevalence of SAD, with up to 10% of the population in far northern countries suffering from some of its symptoms.
While one explanation for SAD is that people tend to be less physically active during cold weather, another factor that comes into play is simply the amount of light received by the eyes. Low light levels discourage the production of the neurotransmitter serotonin, which has important effects on mood. Dim illumination and darkness also produce high levels of melatonin, which makes us feel sleepy and less energized. Interestingly, there are nerve connections linking the eye’s retina and the Pineal gland in the center of the skull, which is where melatonin is secreted.
Treatment for Seasonal Affective Disorder often follows similar approaches to that of clinical depression, but there is also a simple solution at our disposal. Artificial lighting, in addition to generally being dimmer than direct sunlight, is also a different color – white light is actually a mixture of several colors and normal light bulbs emit less blue than the sun and daytime sky do. One way of combating SAD is just sitting in front of a “light box” which provides strong illumination that stimulates brain chemical production in much the same way as real sunlight can. Doing so may be a little inconvenient, though. Instead of merely using a lamp to illuminate a room, the recommended use is to sit in front of the light box for an hour per day, perhaps while reading a book.
In human society, before fire was discovered, we tended to get up at dawn and go to sleep at dusk. Then, doing otherwise would have meant running the risk of walking over cliffs or stumbling onto hunting predators. Even though these risks are minimal today, our bodies have not yet adjusted to being able to work and play during night time and our body’s instincts regarding when bedtime is approaching are heavily dependent on the kind of light the eye perceives.
Our internal circadian rhythm – the biological clock that tells our body where we are on a 24-hour cycle – affects the function of an estimated 10% of our genes, so messing with it too badly cannot be good for either our mental or physical well-being. In particular, the quality and quantity of sleep we get are extremely important to our health.
While lifestyle aspects such as stress, excessive caffeine consumption and lack of exercise all play a role, our internal time is basically calibrated by dawn and dusk. As with Seasonal Affective Disorder, it’s not only a question of how much light is around us but also its color. Blue light, in particular, suppresses melatonin levels and can cause insomnia, while reddish light – as you would see around the time the sun goes down – has a lesser effect on our ability to go to sleep.
As it happens, most computer and phone screens emit excessive amounts of blue light, meaning that spending and browsing through Reddit just before going to bed can keep you unwillingly awake for longer. Luckily, there is a technological fix for this: apps such as f.lux alter the color balance on your monitor depending on your location and the time of day, making the trip to dreamland easier after working late.
Vitamin D and Health
Some vitamins like vitamin C can’t be naturally produced by our bodies and have to be absorbed from what we eat. Vitamin D, on the other hand, is synthesized in our skin when sunlight falls on it.
Many of the effects of insufficient levels of vitamin D are related to the way it helps our bodies work with calcium, including the skeletal condition known as Rickets. Long before such a major deficiency becomes apparent, though, a vitamin D shortage can affect our mental state. Calcium, too, plays a vital role in nerve cell functioning. Having too little vitamin D and therefore insufficient calcium can contribute to diseases such as clinical depression, while vitamin D deficiency in children can even negatively affect their brain’s development. There are a number of foods that can help a person obtain the vitamin D necessary for good mental and physical health, but the simplest solution may be to take a walk in the park, or go lie on the beach for an hour.
Telling someone with major depression to “lighten up” is not the most helpful thing you can do, but it turns out that light does indeed have a major influence on how we feel. Keep this in mind the next time you buy light bulbs, or when choosing between an outdoor activity and staying in this weekend.