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‘The SAD season’ arrives as sunlight wanes

Shortened duration of sunlight and reduction of intensity can result in depressed mood

CHICAGO --- Feeling emotionally meh or downright melancholy? The SAD season has arrived as the duration and intensity of sunlight wanes, often affecting our mood, says a Northwestern Medicine expert in light and mood.

Dr. Dorothy Sit, associate professor of psychiatry and behavioral sciences at Northwestern University Feinberg School of Medicine, discusses how the SAD (Seasonal Affective Disorder) season affects our mood and what to do about it.

“The seasonal mood change can come in different shapes and forms,” Sit said. “It can be a clinical diagnosis of depression, which we call SAD, but some people experience a milder form. The clinical diagnosis means it is quite intense; it affects people all day for many weeks and can impact their functioning. In milder cases, people can feel a bit blah, but can push through. Still, functioning will feel a bit harder.”

Feeling tired and sluggish

“People may experience a slight dip in their mood, feel a little depressed and less motivated. Their enjoyment of activities can be impacted. They can feel more tired and sluggish. They may find themselves sleeping more to combat the fatigue. They may feel hungrier, have carbohydrate cravings, eat more and gain weight.

“This is a form of depression that cycles naturally; it starts every fall and winter and remits every spring and summer.”

Bright light therapy is the antidote

Bright light therapy is the most effective treatment for winter-related depression, Sit said. She recommends a unit that produces 10,000 LUX of white light to be used in the morning for 30 minutes after waking up.

“The treatment provides an uplift in the mood, improves a person’s functioning and may completely resolve their symptoms. It’s even effective for non-seasonal depression, depression in pregnancy and in certain people with bipolar depression.”

Other advice from Sit to combat winter blues:        

  • Stay active in healthy ways, taking hikes with the family, exploring nature, exercising, learning a new skill, visiting a museum.
  • Protect your sleep. Maintain a regular sleep-wake schedule. Limit naps to 20 or 30 minutes to restore your energy, but don’t oversleep.

Why light boosts your mood

“Light from the sun (sunlight) is the primary regulator that provides the signal for our bodies’ circadian rhythms. Not having significant exposure to light can affect that. Bright light therapy is used in a way to amplify our circadian rhythms, which appears to boost our mood. Timing the light so the exposure is first thing in the morning may produce more of an impact to regulate our rhythms. We are still trying to fully understand how this mechanism works.”

Sit, who researches light therapy for individuals with bipolar disorder, warned about potential problems for people with undiagnosed bipolar disorder using light therapy. These individuals first need a mood stabilizer before they can be considered for mid-day light therapy, which is a novel but effective timing for them. Careful monitoring is advised for people who intend to pursue bright light therapy. A physician or clinician can observe for a proper response, detect any side effects or problems that arise, and discuss alternatives if indicated.