Seasonal Affective Disorder

Attributes that may increase your risk of SAD include:

• Being female. Women are four times more likely to report SAD
• Living far from the equator increases the risk of developing SAD
• 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.
• Darker and colder weather may exacerbate present mood disorders in the winter months.
• Younger adults are at greater risk of SAD than more mature adults. Even children and teens report experiencing SAD.

The causes of SAD are unknown, but research has found some biological clues.

• People with SAD often have difficulty regulating one of the critical neurotransmitters of mood, serotonin. A study found that people with SAD have five percent more serotonin transporter protein in winter than in summer. Higher serotonin transporter protein leaves less serotonin available at the synapse because the function of the transporter is to recycle neurotransmitters back into the pre-synaptic neuron.
• People with SAD may overproduce the hormone melatonin. In the winter months, more darkness increases the production of melatonin, which regulates sleep.
• People with SAD also may produce less Vitamin D. Vitamin D is believed to play a role in serotonin activity. Vitamin D insufficiency may be associated with clinically significant depression symptoms.