Winter time is upon us, which can mean an increase in Season Affective Disorder, also known as S.A.D. For those in the northern climates, where it is cold and the reduction of sunlight during the day effects mood, it can be devastating. Getting regular exericse, eating well, and checking your vitamin D levels to make sure they are adequate can all help with SAD. Additionally, using a full-spectrum light (which mimics the rays of the sunlight) can also help your body and eyes to absorb the “sun” rays. Please read the instructions on the light you purchase. A standard full spectrum light has 10,000 Lux, and the standard use is to have it slightly above eye level, start with 15 minutes a day and work up to 30 minutes every day. Do NOT stare right into it! Many models have a lower and higher modes, this one has a “white” and “blue” mode. There is debate as to whether these lights can help, but it has been a standard recommendation in psychiatry and psychology for years to boost and imitate the outside sunshine light.
Sitting in front of a sunny window during winter can also help. Hats off to those in warm climates who can be outside during winter months! In the mean time, this can be a postive therapeutic to help if you suffer from low energy, feeling “blue” or down during the long winter months. 
Please note that I am not endorsing this specific lamp nor do I get anything from posting this particular one, it just happens to be the one I bought.