By Stephanie Stahl

PHILADELPHIA (CBS) –It’s another gloomy day in the Delaware Valley. And many are starting to get bit by the winter blues. 3 On Your Side Health Reporter Stephanie Stahl has more on how to beat it.

Seasonal affective disorder, also known as SAD, is a type of depression that occurs at the same time every year, when there’s less light. It happens more often in women than men. But there are things you can do to help you get through these more gloomy months.

Winter has been different this year with all the rain and no snow. But no matter what’s falling, we get less sun during the winter season, and sunshine is the main source of Vitamin D.

“The big factor is the sun does not go as high up in the sky, and as a consequence, the light that reaches us is much weaker,” said William Shaw, a toxicologist.

Lack of Vitamin D can lead to Seasonal Affective Disorder. Experts believe reduced sun can also disrupt your body’s internal clock and cause serotonin, a feel good chemical in your brain, to drop causing the depression.

Chef Travis Napier cooks more fish in the winter to boost his vitamin levels.

“Vitamin D and fish, they kind of go hand in hand. A couple of species that we have on the menu now such as salmon and tuna are very high in vitamin D,” said Travis.

Doctors say other ways to beat the blues are to drink fortified milk, take Vitamin D supplements, get outside more and exercise.

“These simple steps can be the difference between having a happy winter and one that’s associated with depression,” said Shaw.

If you’re having problems with SAD be sure to speak with your doctor. Prescription medication and light therapy can help treat the condition.

Seasonal Affective Disorder: www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002499 and www.nlm.nih.gov/medlineplus/seasonalaffectivedisorder.html