What is Seasonal Affective Disorder?

Seasonal Affective Disorder or SAD, a form of depression, is now increasingly recognised as a medical condition thanks to the pioneering work of Dr. Rosenthal in the 1970's.

Current statistics show this seasonal form of depression affects over 2 million British people, with the onset commonly occurring between ages 18-30. Recent research has indicated that women may be slightly more susceptible to developing SAD, although as more men become aware of the existence of SAD these statistics may change. Interestingly, SAD has also been linked to bulimia nervosa, an eating disorder, with many people afflicted with this condition; tend to feel worse during winter months, with their symptoms increasing in severity.

Symptoms of SAD

• Lethargy & Lack of Motivation
• Fatigue & Tiredness
• Depression & Hopelessness
• Excessive appetite
• Weight gain

Seasonal Affective Disorder is often referred to as the �Winter Blues�, due to its onset around October and subsidence in April. The condition is related to the amount of light that we receive during the day. Throughout the summer months the average daily amount of sunlight is above 10 hours, whereas during the winter months this can drop to below 8 hours and sometimes less on a dreary winters day. Although this may not seem a dramatic decline in sunlight, it is enough to affect our brain function and mood. To explain this we need to know a little about the effect sunlight has on the brain.

The interaction of light with the eyes affects our brain chemistry by controlling special brain chemicals, or neurotransmitters, called serotonin and melatonin. The actual processes within the brain are very complex, but a simple explanation may help. Serotonin is our "feel-good" neurotransmitter. When there are adequate amounts of serotonin being released within the brain our mood will be positive and happy. However, if these levels drop our mood can change quite dramatically, causing us to feel negative, unhappy and withdrawn.

Scientists have discovered that serotonin levels in the brain naturally drop in the winter months, with some people experiencing greater declines than others. The neurotransmitter melatonin, in simplistic terms, controls our internal clock, regulating our sleep cycle. Serotonin and melatonin work together in the brain, and disturbances in their activities can result in depression. This can cause our sleep pattern to become erratic and the quality of sleep to deteriorate, giving that groggy feeling in the morning, or difficulty getting to sleep at night. Interestingly, animals also experience this drop in serotonin, and scientists believe it acts as a trigger for them to migrate or hibernate through the winter. Unfortunately this is not an option for us humans! So, what are the treatment options for SAD?

Conventional medicine often offers special drugs called 'selective serotonin reuptake inhibitors' or SSRI's. Naturally serotonin is re-absorbed by the parts of the brain that release it. This means that the serotonin can be re-used. The SSRI's work by preventing the re-absorption of serotonin thereby increasing the amount that is active within the brain. This action results in high serotonin levels, and therefore affects our mood, causing feelings of increased happiness and contentment. SSRI's are the common treatment for many depressive conditions, and bulimia nervosa is also treated this way. Studies show SSRI's to be effective in treating SAD, however, the side effects that accompany these drugs are not desirable. Commonly people suffer from loss of appetite, despondency, loss of libido, headaches and digestive problems, amongst others. Additionally dependence can occasionally result from long-term use. The beauty of alternative treatments for SAD, such as light boxes or SAD lamps, is that they are totally safe and do not have adverse side effects.

What is light therapy?

Scientists looking at neurotransmitter activities in the brain decided to see if extra light through winter could help with SAD. The consensus seems to be a strong YES. Patients with SAD exposed to extra daytime light, experience relief from their SAD symptoms, and their mood improves dramatically. It appears that by providing extra natural light the levels of �feel-good� serotonin increase, causing us to feel happier and more positive. This possibly explains why light therapy helps with bulimia as well, as this condition is also linked to low serotonin levels in the brain. The light generated by a good quality light box is called �full spectrum� light. Full spectrum light is natural light. Additionally melatonin levels are suppressed by light (melatonin levels increase with darkness, and are the chemicals that make us feel sleepy at night). This dual action of the light improves our mood and regulates our sleep, or circadian rhythm. To gain the maximum benefit from the light it is important, especially with the desktop lamps, to position them correctly. The light needs to hit a certain part of the retina, this is the innermost layer of the eye where light is absorbed. Where the eye lies next to the nose is the optimal light absorbent area, called the nasal retina. Therefore, placing your light box or SAD lamp to the side of you will get better results than having it directly in front of you. For desk bound workers, a desktop SAD lamp may be the best option as the person can get the required treatment whilst working at their desk.

The sunrise bodyclock by Lumie simulates dawn by waking you with light, and can also have dramatic effects. We can probably all identify with dragging ourselves out of bed on dark winter mornings, feeling as though it's still the dead of night. A sunrise simulating alarm clock is programmed to give out light of increasing intensity over the waking period in the morning. This mimics a natural summer sunrise, allowing a natural arousal from sleep. It appears that our eyes are more sensitive to light first thing in the morning, having maximal effect on increasing those serotonin levels. Whether it is a sunrise or desktop lamp the beneficial effects of this extra natural light are well documented, helping many overcome their winter blues.

In our less than sunny, dismal British winters (and sometimes summers!), the use of SAD light boxes or lamps could help many sufferers of this seasonal depression. Furthermore, light therapy can be useful for those who do shift work or work in environments where natural light is absent or limited, such as basement offices or shopping centres. This is a safe, natural way to enhance wellbeing throughout the winter months, offering hope to those who dread the looming end of summer!

References

• Visser EK, Beersma DG & Daan S (1999) Melatonin suppression by light in humans is maximal when the nasal part of the retina is illuminated. Journal of Biological Rhythms 14, 116-21
• Lambert GW, Reid C, Kaye DM, Jennings GL & Esler MD (2002) Effect of sunlight and season on serotonin turnover in the brain. The Lancet 360, 1840-42
• Johnson R & Somers S (1994) NIMH, JAMA Shed Light on Seasonal Affective Disorder. Psychiatric Times [text only]
• Lam RW, Levitan RD, Tam EM, Yatham LN, Lamoureux & Zis AP (1997) L-Tryptophan Augmentation of Light Therapy in Patients with Seasonal Affective Disorder. Canadian Journal Of Psychiatry 42, 303-306