Light relief for long-term depression

There’s emerging evidence that sitting near a bright light every morning could help people with depression (see recent Cochrane review). More dubious is the suggestion that ‘negative ion generators’ – gadgets that purportedly increase the concentration of negatively-charged atoms in the atmosphere – might also help relieve depression. Namni Goel at Weslyan University and his team tested both these treatments with 31 patients who had been diagnosed with major depression lasting at least two years.

Patients were tested at different times of the year to control for seasonal effects. Ten patients used a fluorescent lamp and 12 patients used a “high density” ion generator. As a control, 10 patients used a “low density” ion generator that had a negligible effect on the air. Participants were asked to use their allocated treatment for an hour every morning for five weeks. The patients obviously knew whether they’d been allocated to the light treatment or not, but those allocated to the ion generator treatment didn’t know what kind of generator they had (high or low density) and the researchers were blind to which patients were allocated which treatments.

Fifty per cent of patients in the light treatment and high-density ion generator groups experienced remission from their depression, the researchers reported, whereas none of the patients with the low-density generator experienced remission. These effects didn’t depend on the time of year, nor were they explicable by changes to the patients’ body clock (i.e. their circadian rhythm) as measured by melatonin levels in their saliva. The researchers suggested the treatments might work because they raise levels of serotonin, the neurotransmitter that is also the target of many antidepressant drugs.

“Light and negative air ion therapies may particularly benefit patients who discontinue, cannot tolerate or show inadequate response to medication”, the researchers concluded.

Goel, N., Terman, M., Terman, J.S., Macchi, M.M. & Stewart, J.W. (2005). Controlled trial of bright light and negative air ions for chronic depression. Psychological Medicine, 35, 945-955.

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.