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Sunshine curbs SAD - Seasonal disorder is treatable with light

Sunshine curbs SAD Seasonal disorder is treatable with light

We are fortunate to have sunshine most of the year. That’s why seasonal “snowbird” residents flock to the Sunshine State from colder climates. Bonus: They are likely avoiding seasonal affective disorder, or SAD.

Medically, SAD is described as a combination of biological and mood disturbances associated with seasonal patterns of depressive symptoms that usually occur during the fall and winter months. Full remission of symptoms usually occurs in spring and summer months.


There are several hypotheses on the cause.

  • The photoperiod hypothesis refers to the dark/light cycle — shorter winter days and less light can lead to more melatonin production, which induces SAD.
  • The phase-shift hypothesis proposes there is an optimal relationship between the timing of circadian rhythms, including melatonin production, body temperature, cortisol (major anti-stress hormone) and sleep. Circadian rhythms that drift with the light changes of winter may misalign these.
  • Retinal sub-sensitivity proposes patients with SAD have an impaired retinal response to changing light and may experience circadian rhythm dysfunction. Light therapy has been an effective treatment.
  • Abnormally low serotonin levels (brain chemical that calms or uplifts) have been found in patients with winter depression.


A diagnosis of SAD is made by determining that symptoms have occurred for at least two years during the same season, that symptoms disappear when the season is over, and that no other mental or physical health problem exists.

SAD (and non-seasonal depression) both consist of major depressive episodes involving low mood, loss of interest or pleasure in activities, change in appetite or weight, low energy, insomnia or hypersomnia, poor concentration, thoughts of worthlessness or guilt, and thoughts about death or suicide. Patients may also desire to eat more.


Light therapy is the least invasive, most natural, and most studied therapy for SAD. Also called bright-light therapy or phototherapy, it produces intensity of at least 2,500 lux at eye level. Light on a northern winter or rainy day is about 2,000 lux, whereas direct sunlight provides about 10,000 lux.

Light therapy diminishes melatonin levels, may normalize the phase-shift delay and has a positive response rate of up to 70%. Light boxes are available for purchase.

Another treatment is dawn simulation, where a light slowly increases in intensity 30 minutes or more before awakening. Antidepressants can be effective, as well.


Hypericum extract, known as St. John’s wort, has been effective in treating SAD. But a pharmacist or physician needs to assess if this is an option since St. John’s wort may affect other medications.

Melatonin has been shown to significantly improve quality of sleep and vitality in SAD patients. Low levels of vitamin D also have been associated with SAD and can be adjusted with vitamin D supplements.

Simple lifestyle changes can have a positive impact, too.

  • Limit starches and sugars
  • Add exercise
  • Manage stress
  • Avoid social withdrawal
  • Spend more time outdoors
  • Have good sleep hygiene

Sleep hygiene consists of creating a regular light/dark cycle. Set a routine bed time, keep your sleep environment comfortable, avoid eating late dinners or drinking lots of fluids prior to sleep. Minimize light exposure two hours prior to bedtime, including limiting exposure to the blue light that emanates from computers, TVs, and cell phones.


Edward  H. Nessel  has a doctorate  in clinical pharmacy  and is a biochemist and physiologist. He is a published author and and has  been a swim coach for over 50 years, coaching seven  Olympians in that time. He still trains in the pool several days a week and coaches others in his “retirement.” Visit or  email  him at


Read more articles in our DIGITAL MAGAZINE.


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