What light therapy is
Winter-pattern seasonal affective disorder (SAD) is depression that returns in the darker months and lifts in spring. NIMH describes light therapy as a mainstay of treatment for it since the 1980s. The idea is simple: a very bright light box makes up for the reduced natural sunlight of fall and winter.
NIMH lists four main treatments for SAD, used alone or together: light therapy, psychotherapy, antidepressant medication and vitamin D. Light therapy and vitamin D are specific to the winter pattern; therapy and antidepressants treat depression more broadly. If you are not sure whether what you feel each winter is SAD, Seasonal Depression and Michigan Winters covers the signs and why Michigan's dark months matter.
What a light box is, and what to look for
A light box is not an ordinary lamp. According to NIMH, it gives off 10,000 lux, about 20 times brighter than ordinary indoor light, and filters out potentially damaging ultraviolet (UV) light. Cleveland Clinic describes the typical design as white fluorescent tubes behind a plastic screen that blocks UV rays.
- Brightness: 10,000 lux is the standard both NIMH and the NHS cite.
- UV-free: the NHS advises choosing a light that is UV-free.
- Size and setup: you need to be able to sit near it daily while doing something else, such as eating breakfast or reading.
- Not a tanning bed: Cleveland Clinic says not to use tanning beds for SAD, because their high UV output can hurt your skin and eyes.
How to use it
Guidance varies a little by source, which is one reason to plan it with a clinician:
- Timing: morning works best, according to Cleveland Clinic, and using it later in the day may cause insomnia. NIMH says usually first thing in the morning.
- Length: NIMH describes about 30 to 45 minutes a day; Cleveland Clinic notes many health professionals recommend 15 to 30 minutes each morning at 10,000 lux.
- Position: Cleveland Clinic advises indirect exposure. Do not stare into the light; place it about two to three feet away while you do other things.
- Season: NIMH describes daily use from fall to spring. Cleveland Clinic notes providers often recommend continuing through the whole winter, because symptoms can return quickly after stopping.
A realistic routine for a Michigan winter morning might be the light box on the kitchen table during coffee and email, at the same time each day, including weekends. Consistency is easier when it is attached to something you already do.
How quickly it works
Cleveland Clinic reports that people who use a lamp for SAD often see results within two to four days, and it may take about two weeks to reach full benefit. If you have used it consistently for a few weeks and feel no different, that is useful information to bring to your doctor or therapist, not a sign you did it wrong.
Light therapy can also be combined with other care. NIMH notes the SAD treatments can be used alone or together. The adapted therapy NIMH describes, known as CBT-SAD, also uses behavioral activation: deliberately scheduling pleasant, engaging indoor or outdoor activities to offset the loss of interest many people feel in winter. That idea is worth borrowing even on days the light box is the only treatment you are using.
How it compares with other treatments is worth knowing. NIMH describes research in which a version of cognitive behavioral therapy adapted for SAD and light therapy were equally effective, with some symptoms improving slightly faster with light. A long-term study that followed patients for two winters found the benefits of the therapy seemed to last longer. The evidence is not settled everywhere: the NHS says light therapy is not usually available on the NHS because there is not enough evidence to tell whether it is effective, though many people find it helps.
Who should check with a doctor first
NIMH calls light therapy safe for most people, but notes that some may need alternatives or medical supervision. Talk with a doctor before starting if you:
- Have an eye or retina condition, or diabetes, which Cleveland Clinic notes carries a potential risk of retinal damage
- Take medicines that increase sensitivity to light, such as certain antibiotics or anti-inflammatories
- Have bipolar disorder or have had periods of unusually high mood or energy; Cleveland Clinic notes bright light, like antidepressants, can trigger hypomania or mania
Side effects Cleveland Clinic lists include eyestrain, fatigue, headaches, insomnia and irritability. Mention any of these to your doctor, who can help you decide whether to change how you use the light.
Starting before symptoms do
Because SAD tends to arrive at the same time each year, NIMH notes that people with a history of it might benefit from starting treatment before fall, although few studies have tested prevention. Cleveland Clinic similarly suggests beginning light therapy at the start of fall, before symptoms appear. If you know your low point usually comes in November, a conversation with your doctor in September is reasonable.
When light is not enough
Light therapy is one tool. If winter depression is affecting work, relationships or safety, or returns year after year despite a light box, talk with your doctor about the other treatments NIMH lists. Therapy can address the patterns that winter tends to deepen, such as withdrawal and self-criticism. Depression therapy with Dr. Lehmann is available in person in Franklin or by telehealth for clients located in Michigan, which can help on icy mornings.