SAD Light FAQS (19 Frequently asked questions)

1. What are winter blues and seasonal affective disorder (SAD)?

Winter blues refers to a set of symptoms many people get in the short daylight months- typically September to March- including sadness, fatigue, decreased libido, difficulty concentrating, irritability, increased sleep and appetite, carbohydrate craving and weight gain.  SAD is the severe form of winter blues, so that you become clinically depressed and the other symptoms become seriously debilitating.  A key feature is that symptoms appear as daylight decreases in the fall and disappear as daylight increases in the spring.

2. How common are winter blues and SAD?

As one might expect, winter blues and SAD are more common as you move further from the equator.  Winter days are shorter and daylight decreases as you move toward the North or South Poles.  Perhaps 25% of people in the northern US & Canada suffer from winter blues, with about 15-30% of these having SAD.  People living in lower latitudes may also experience winter blues if they spend their days in offices that are typically much less bright than the outdoors, or if their winter weather is cloudy.

3. What is a circadian rhythm?

We all have an internal clock that determines our wake/sleep cycle, or circadian rhythm.  This circadian rhythm normally matches our day/night cycle, but may be disrupted by jet travel across time zones, work shift changes (day shift to night shift and back again), or some insomnias where our sleep phase gets “out of sync”.  When you circadian rhythm is disrupted, you suffer fatigue, decreased concentration and productivity, and increased work errors.

4. What is light therapy?

Light therapy is the shining of bright light into your eyes-typically for a half hour each session.  Since the 1980’s, light therapy has become the first line treatment for winter blues and SAD.  Bright light can also be used to shift your circadian (wake/sleep) cycle, so it is used to prevent jet lag, minimize work shift change fatigue, and help abnormal sleep phase insomnias.

5. How does light therapy work?

We know that shining bright light into your eyes:
a) suppresses brain melatonin, causing wakefulness, and
b) enhances brain serotonin, causing mood elevation.
Light therapy takes advantage of these effects to alter your circadian rhythm to prevent jet lag and work shift change fatigue and some insomnias, as well as to treat winter blues and SAD.

6. How much light is best?

Light therapy is measured in lux, which is measured of the intensity of light as perceived by our eyes.  Typical room light intensity is several hundred lux.  Light therapy began years ago with what we now consider to be low doses-500-2500 lux- for 1-2hours.  Studies showed that treatment times can be reduced by increasing the light dose.  Now, 10,000 lux for ½ hour is considered by many to be a standard dose.  The Feel Bright Light brackets this “standard dose” by providing 8,000 or 12,000 lux so you can adjust to surrounding light conditions while receiving a very effective dose.

7. How can I compare light doses between different devices?

Each device manufacturer publishes the intensity of their device (usually in lux) as measured at the recommended distance from your eyes.  So, the lux from a portable device that is 1-2 inches from your eyes is comparable to the lux of a desk-top device that is 18 inches from your eyes, etc.

8. What time of day is best?

For winter blues, a bright light session shortly after arising in the morning works best for most people.  Some people benefit from an additional session in the late afternoon.  Bright light use in the evening may disrupt your sleep pattern.  For circadian rhythm shifting, i.e. jet lag, shift work, and sleep phase insomnias, the time of day to use bright light depends on whether you want to shift your circadian clock forward or backward.

9. What type of lamp is best?

The best lamp provides:

  • high intensity;
  • maximum full spectrum, uv-free;
  • focused light to make the best use of the available light;
  • long life;
  • More functions, such as wake-up light with sunrise, sleep light with sunset..

10. Should I use light?

Reasons to consider bright light:
Most people with winter blues are likely to respond well to light.  If your symptoms are severe, you may suffer from SAD.  Light therapy may work well for you, but you should consult with your clinician before choosing any therapy.  Bright light can be used along with other treatments- e.g., antidepressants for SAD.  Likewise, most people will respond to light for circadian rhythm adjustment- i.e., jet lag, shift change work, and some insomnias.

Reasons to not use light:
Generally, bright light is very safe. If you:
a) have any eye disorder (e.g., cataracts, glaucoma, retinal disease),
b) have any disease with high risk for eye problems (e.g., diabetes, lupus),
c) have any problem triggered by bright light (e.g., migraine),
d) take photosensitizing medication (e.g., certain psychiatric drugs, melatonin), you should consult your clinician prior to starting bright light sessions.