What is SAD

SAD, Seasonal Affective Disorder, or in its most common form, Seasonal Depression, is a form of clinical depression which manifests itself in the winter months. It can also be called winter depression. Left untreated, the symptoms will usually resolve as the days get longer in Spring and Summer. However it can be very life-limiting for the sufferer while it is ongoing, and if severe it can last beyond the dark winter season, and leave the sufferer open to bouts of depression at other times of the year. 

As with all depression, suicide can be a risk.

The Symptoms of SAD

The symptoms of SAD are very similar to depression but they typically begin during Autumn, stretch on through Winter, and begin to get better in Spring

  • Feelings of low mood, hopelessness and sadness.
  • Low energy levels and the feeling of need for more sleep but not being refreshed by it.
  • Lack of interest in normal pursuits and social isolation
  • Weight gain due to cravings for sweet and energy rich foods
  • Increase in alcohol and caffeine consumption
  • Deterioration in concentration and memory

Treatment of SAD.

Cognitive behavioural therapy and light therapy are both used to treat Seasonal Affective Disorder, and have both been shown to be as effective as antidepressant drugs for mild to moderate disease. There are also many things you may do to help yourself if you suffer from SAD.

More severe seasonal depression may need to be treated with medication, or even hospitalization. This article will focus on light therapy.

Why Light Therapy?

SAD or Winter Depression is caused not by the cold, the wet, or any other depressing feature of winter, but instead it is brought on by lack of light or possibly shortening day length. (Many Northern countries report a surge in calls to suicide help lines, and even suicides, in late summer and early Autumn when there is still plenty of light in the day).

In winter as you move northwards, away from the equator, the days get shorter and shorter, until far North, in Arctic regions, in midwinter, there is no day length of any significance at all. People who move from areas nearer the Equator, such as Mexico or North Africa to Northern America or Northern Europe, are far more likely to experience seasonal depression than those who stay where they are. More interestingly, those who move back will soon see a reversal of those symptoms.

If you look at the diagram for day length in London, UK, (the blue line), you will see that a citizen of London undergoes a change in hours of daylight from under 17 hrs of daylight in summer to just under 8 hrs in Winter. That is a change of  9 hours in 6 months, or approximately 20 minutes per week, surely easily recognisable by our inner clocks.

In Winter the light is also not as intense, as the sun is lower in the sky.

Daylength in London Throughout the Year

Light Therapy

The aim of light therapy is to fool the body into thinking that it is closer to summer than it has observed by the light it is exposed to each day. This is done with bright lights directed at the open eyes, usually in the morning shortly after getting up. The brightness of the lights has to be in the region of about 10 000 lux at the surface of the eye, with a treatment time of 30 minutes to one hour. Lights of lower intensity (no lower than 5000 lux) may be used, but that requires a longer treatment time. If any treatment light is used further than the recommended distance from the face, then the brightness of the light drops off quickly and again longer than usual treatment times will be needed.

Light Therapy Box

A light therapy box, also known as simply a lightbox (not to be confused with the photographic apparatus), a seasonal affective light, or an SAD Lightbox is a piece of medical apparatus, which is engineered precisely to deliver the required light intensity at a specific distance from the eye. It will not produce harmful light, and the light will usually be diffuse enough that it will not cause eyestrain if used as directed.

It is not to be confused with the many other 'light therapy' products which are often no more than a full spectrum bulb (or not even full spectrum) in a fancy looking lamp. These are understandably cheaper, but you would be as well off going down to the electrical store, buying a cheap lamp and screwing a brighter lightbulb into it. It won't help.

It is possible to get a bargain, by buying an old model, a soon to be replaced one, or a second hand or showroom model. It may also be possible for a few people to club together to buy one, or you may decide the whole family could benefit, not just one person. A large model at the breakfast table will get everyone's day off to a brighter start.

If buying from the internet beware of fakes. If it looks to good to be true, it probably is. This is a piece of equipment which could last for years, so imagine dividing the cost over the next five or ten winters!

Many doctors have contacts in the manufacturing companies, and are able to get a loan of a lamp for a few weeks for patients to try out before making their purchase.

Making a Light Therapy Box

It is possible to make a SAD lightbox, and there are many sites online which will give you directions. If you choose to go down that route however, it is best to purchase the bulbs direct from one of the companies that supply medically approved Seasonal Affective Disorder Therapy Lights. Such companies usually sell the bulbs as spares, and they can also offer the fittings to replace overheated or damaged ones.

The reason for buying from a reputable supplier is that you don't want a light that is pumping out damaging light which could harm your retina or cornea.


The Cheapest Light Therapy

Of course the cheapest light therapy for SAD is free. Unless you live so far from the equator that in winter your daylight dwindles to nothing, there will be a significant amount of daylight available on even an overcast day. The best time to get some of that light is in the middle of the day, generally between 11 am and 2 pm. Of course many people are stuck indoors at work or school at that time, but fortunately the brightest time of day also corresponds with most people's lunch breaks. So it is well worth taking a trip outside to make the most of the light at that time of day. On a sunny day the light striking your eyes from the sky is well in excess of the necessary 10 000 lumens, and you are also benefitting from exercise and fresh air. Both of which can cause mood elevation.

If you are really stuck indoors because for example of illness or injury, then it is useful to be seated near a south-facing window between eleven and two. A bay window or a large ceiling window is even better, the first will surround you with light, the second provide unshaded light from above.

Even on an overcast day, it is brighter indoors than out.(65873)


If you suffer from seasonal affective disorder, and you think that you would benefit from light therapy, please do not suffer just because it seems to be out of reach financially.

I hope the article above will have shown you that it is well worth a try, and with a bit of creative thinking, may not cost the earth.