Beyond the Winter Blues

Seasonal affective disorder (SAD) is a type of depression that comes and goes with the seasons. It usually starts in the late fall and early winter and goes away during the spring and summer. Some people do have episodes of depression that start in the spring or summer, but that is much less common.

Symptoms of SAD may include sadness; a gloomy outlook; feeling hopeless, worthless, and irritable; loss of interest or pleasure in activities you used to enjoy; low energy; difficulty sleeping or oversleeping; carbohydrate cravings and weight gain; and thoughts of death or suicide.
The causes of SAD are unknown, but research has found some biological clues. People with SAD may have trouble regulating seratonin, one of the key neurotransmitters involved in mood. One study found that people with SAD have 5{06cf2b9696b159f874511d23dbc893eb1ac83014175ed30550cfff22781411e5} more serotonin transporter protein in winter months than summer months. Higher serotonin transporter protein leaves less serotonin available at the synapse because the function of the transporter is to recycle neurotransmitter back into the pre-synaptic neuron.
In addition, people with SAD may overproduce the hormone melatonin. Darkness increases production of melatonin, which regulates sleep. As winter days become shorter, melatonin production increases, leaving people with SAD feeling sleepier and more lethargic, often with delayed circadian rhythms.
People with SAD also may produce less vitamin D, which is believed to play a role in serotonin activity. Vitamin D insufficiency may be associated with clinically significant depression symptoms.
Attributes that may increase the risk of SAD include:
• Being female. SAD is diagnosed four times more often in women than men.
• Living far from the equator. SAD is more frequent in people who live far north or south of the equator. For example, 1{06cf2b9696b159f874511d23dbc893eb1ac83014175ed30550cfff22781411e5} of those who live in Florida and 9{06cf2b9696b159f874511d23dbc893eb1ac83014175ed30550cfff22781411e5} of those who live in New England or Alaska suffer from the condition.
• Family history. People with a family history of other types of depression are more likely to develop SAD than people who do not have a family history of depression.
• Having depression or bipolar disorder. The symptoms of depression may worsen with the seasons if an individual has one of these conditions (but SAD is diagnosed only if seasonal depressions are the most common).
• Younger age. Younger adults have a higher risk of SAD than older adults. SAD has been reported even in children and teens.
The main treatment for SAD is light therapy. The idea behind light therapy is to replace the sunshine missed during the fall and winter months. The individual sits in front of a light-therapy box every morning to get daily exposure to bright, artificial light.
However, some people with SAD do not respond to light therapy alone. Antidepressant medicines and talk therapy can reduce SAD symptoms, either alone or combined with light therapy.