Mental health articles

The recognized treatment of Seasonal Affective Disorder (SAD) is known as ‘bright light’ treatment which lowers levels of melatonin. In this, the individual is typically exposed to high levels of artifi cial light, varying from 2500 lux for a period of 2 hours to 10  000 lux for half an hour each day over a period of between one and three weeks. For comparison, light in the house typically measures 100 lux or less. Outside lux levels may vary between 2000 lux or less on a rainy winter day and 10  000 lux in direct sunshine. Exposure is increasingly done in the morning to help shift individuals into an appropriate melatonin day–night rhythm.

These interventions can be effective. Sumaya et al. reported a trial in which participants were subject to three conditions in a random order: (i) a therapeutic dose of 10  000 lux for 30 minutes daily for one week: (ii) a non-therapeutic dose of 300 lux over the same time period (placebo): (iii) and a no-treatment period. After light treatment, 50 per cent of those receiving the active treatment no longer met the criteria for depression. Levels of depression did not change following either the placebo or no-treatment phases. Building on this success, more recent studies have tried to fi nd the optimal wavelength of the light to improve mood. In one such study, Strong et al. compared the effects of short wavelength light (blue light) against dim red LED lights. The blue light proved the more effective of the two.

Despite these successes, not all studies have proven light therapy to be effective. Wileman et al. randomly allocated people with SAD to either an active (four weeks of 10  000 lux exposure) or what they considered to be a placebo (four weeks of 300 lux) condition. Immediately following treatment, 30 per cent of those in the active treatment and 33 per cent of those in the placebo treatment were no longer depressed; 63 per cent of those in the active group and 57 per cent of the placebo group showed ‘signifi cant’ improvements. The authors took this to indicate either a high level of placebo response among people with SAD, or that the threshold for light therapy was lower than initially thought. Although light therapy remains the pre-eminent treatment for SAD, some people prefer to take medication. SSRI medication results in greater improvements than those achieved by placeboand achieves signifi cant gains among people who have benefi ted little from light therapy. A further candidate treatment involves the use of noradrenaline reuptake inhibitors (NARI) which have been shown to have a similar benefi t to SSRIs.

Tags: disorder, remedies, seasonal sffective disorder