As the nights get longer, those who suffer from the winter blues¹ will be planning ways to escape to the sunshine. But there may be a much simpler way of cheering yourself up... simply shining a bright light into your ear canal.

随着黑夜变长，那些患冬日抑郁的人要开始考虑想办法逃往阳光地带了。不过也许有一种简单得多的方式能让你的心情好起来——只需将一束亮光射进你的耳道就行了。

Up to one in four Britons suffer from seasonal² affective disorder³, with seven percent of the population having full-blown SAD.

It is caused by the brain not receiving enough daylight which is needed to trigger serotonin（血清素） , a hormone⁴ that regulates mood. Symptoms range from mild lethargy（昏睡） to depression and insomnia⁵, but a cure might be in sight.

Two clinical trials, run by Valkee - who make a device that can shine light into your ear - and the University of Oulu in Finland, have found that carefully targeted light can help prevent the condition.

Juuso Nissilä, Valkee's co-founder and chief scientist said: 'We presented earlier that the human brain is sensitive to light.

'These two clinical trials demonstrate that channeling bright light via ear canal（耳道） into brain's photosensitive areas effectively prevents and treats seasonal affective disorder.'

The University of Oulu reported that in their first study, 92 percent of the patients with seasonal affective disorder achieved full remission（缓解，宽恕） after a month of daily eight-to-12 minute doses of light from the Valkee.

Timo Takala, chief physician at the Oulu Deaconess Institute said: 'These two trials show that bright light channeled into the brain via ear canal is an important future method to treat seasonal affective disorder.'

Valkee launched its bright-light headset in August 2010. It is classed as a medical device under EU regulations.

The device channels bright light direct to the brain via the ear canal to prevent and cure depression, mood swings and even circadian（生理节律的） -rhythm disorders⁶ such as jetlag（时差综合症） .

It costs £185 and looks like an iPod - only the earphones emit light rather than sound.