It has been a particularly dark winter so far, don't you think?

We may have been spared the Montreal conditions of two years ago, when snow and ice covered everything for months, but the quid pro quo has been weeks of grey cloud and an oppressively weak light that casts daily life in gloom, as if someone has turned down the sun with a dimmer switch.

How many days have we had since November when the only sure sign that it's morning has been the time on the clock? When it's 9am and dark as an ash cloud outside, it dampens the spirits; when it reaches tea time and hasn't become properly light all day, you go to bed feeling cheated.

That's why light boxes are such a brilliant invention. We bought one a few years back during another dismal winter but haven't used it much since – until now. This year it has given a much-needed shot of good cheer at the start and close of each day. During a dark Scottish winter, many people get the blues, longing for brighter days, while others get seasonal affective disorder (SAD) where they feel withdrawn, depressed, lethargic and suffer sleep problems.

Light boxes emit light equivalent to or greater than the light you would encounter on a clear, bright spring morning. The theory is that light through the eyes stimulates our normal circadian rhythms, helping us feel energised during the day and sleep at night.

A light box of 10,000 lux (a measure of brightness) is about 20 times brighter than a well-lit office. We have ours on over breakfast and occasionally in the early evening, and it does lift the mood – not dramatically, but enough to be noticeable. Is it the placebo effect? If so, who cares, so long as it makes a difference. Not a substitute for real sun, but a welcome reminder of it.