Everyone gets a little blue now and again and this is especially true for many who live in parts of the world where the daylight gets short, the nights get long, and the temperatures plummet. For some however, the blues get much darker and become a type of depression known as seasonal affective disorder, called SAD. This is a very real type of depression and for those who suffer with it, it occurs at the same time every year.

There is no identified cause for seasonal affect disorder, but there are some contributing factors that appear to influence some people more than others. First is each person's biological clock, also called circadian rhythm. Many people are sensitive to the lower levels of sunlight of the fall and winter and this can severely affect sleep patterns. Add to this the artificial time clock change that is daylight savings time in some parts of the U.S. and sleep can be easily knocked awry.

Natural hormones may also be disturbed with seasonal changes. This can particularly play havoc with the hormone melatonin. Melatonin is an agent in sleep patterns and in turn, mood. There are melatonin supplements, both capsules and liquid, that may be helpful, but it is best to check in with a physician first before starting them.

Because seasonal affect disorder is a form of depression and radically affects moods, it makes sense that changes in brain chemicals also play a part in SAD. In particular, the level of serotonin in the brain can be lowered because of reduced sunlight. Serotonin is a large contributor to positive thoughts and mood and if the levels dip, it can lead to depression.

There are a number of treatments now available to help sufferers cope with SAD. Options include medications, counseling and light therapy. Taking the first step to learn more about SAD online is a good way to determine if symptoms warrant further medical treatment.