Seasonal affective disorder is a type of depression. It occurs in the autumn when the days get shorter and the evenings longer and there are less daylight hours. It's commonly known as SAD. Symptoms can last right through until February.
The lack of light during winter can disrupt your body clock, the circadian rhythm. The reduced hours of daylight can trick your brain into thinking that it is night time during the day; this can then cause the symptoms which include: fatigue, persistent low mood, lack of motivation, sleeping more than usual, and feelings of despair and sadness. Appetite can also be affected. You can feel drained and lack motivation.
Vitamin D is an important nutrient to help with mood and the best source is the sun! Unfortunately we don't get enough sun in the summer, and when we do we cover up. In the winter the sun is too low to be of benefit to us. As a result many people are deficient in vitamin D which in turn can impact negatively on melatonin and serotonin levels. For this reason vitamin D is an important vitamin to consider supplementing with.
Other supplements that can help include Omega 3 fish oil, Tyrosine, B Vitamins, and Rhodiola.
Rhodiola is a herb which may improve serotonin levels in the brain. Low levels of serotonin affect energy, and mood. It can cause feelings of depression, and affect sex drive and libido in both males and females. Rhodiola can help improve these symptoms and will also help memory and concentration.
Lack of energy, motivation and drive are also common symptoms associated with SAD. One supplement that I have tried myself to deal with these symptoms is Higher Nature Drive. It contains Tyrosine, and B vitamins which support thyroid function, and also support dopamine levels which are important for motivation. It works brilliantly for me.
Getting plenty of daylight is extremely important, go outside as early as possible in the day, take your break and exercise outside when you can. Open your curtains and blinds to let as much daylight into the room as possible. SAD Light Therapy Lamps are another option worth considering.
Call into your local health store for more advice. They may have other options. Check with your doctor if you're on medication before taking supplements.