“Even at that stage, there will be a few patients – for example those with an eye condition or anyone taking medicines which affect light sensitivity (some antidepressants, and some antibiotics, for example) – who would need to take special care,” she said.

“However if this treatment can be shown to work in a larger study, then light therapy may offer a way forward.”

Professor Eduard Vieta, chair of the Department of Psychiatry and Psychology at the University of Barcelona Hospital Clinic, commented on the study: “Light therapy has been used successfully in the past to treat some forms of depression and this study suggests now that it may also work to treat low sexual desire in men.

“The mechanism of action appears to be related to the increase of testosterone levels.

“Before this kind of treatment, which is likely to be better tolerated than pharmacological therapy, gets ready for its routine use, there are many steps to be implemented, including replication of the results in a larger, independent study, and verifying whether the results are long-lasting and not just short-term.”