Winter blues are a fact of life for millions of people in Britain, especially during those dark, dank months between November and February.

If the cold months get you down and you long for summer climes, it might not be heat you are yearning for, but light.

Lack of daylight can result in overeating, depression and loss of energy. In its extreme form it's even got a name - Sad or Seasonal Affective Disorder

The only cure is a regular dose of strong artificial daylight.

Now a London caf� is offering Sad therapy for weary patrons.

Bright idea

Konditor & Cook is the theatre bar at the Young Vic near Waterloo, in London.

As well as the usual pick-me-ups such as cappuccino and cake, any actors or theatre-goers who need to cheer themselves up can simply switch on the large bright light panel fitted next to each table.

"Coffee and sweet cakes are a natural tonic, but light does much the same thing," says caf� director Mark Ryan.

"It can't be a coincidence that we light bonfires and Christmas lights in November and December. Or that we go for rich foods like Christmas pudding around the same time."

Recently recognised

Scientists say that it's the short days and long nights of winter that create a biochemical imbalance in the part of the brain that regulates many body functions, including sleep, moods and energy levels.

"Light is vital to our well-being. As the days get shorter the body's clock can go out of sync with its rhythm of day and night.

"This can result in very depressing symptoms," says Professor Chris Thompson, head of the mental health group at the Royal South Hants Hospital in Southampton.

It is comparatively recently that Sad has been recognised as a medical condition. Before that sufferers were told to pull themselves together.

Now research has shown that high levels of light in the early part of the day offers benefits to sufferers.

"It is a miracle. After a month you feel fighting fit whatever the weather," said one user.

Stripped down

So far the bright lights of London are proving very popular. There are only three "Sad caf�s" - the others being in Toronto and Helsinki. So customers come to London from as far away as Oxford.

"You can tell those who haven't quite got the idea when they start stripping down to shorts and singlet in the middle of the caf�, like they were on a sun bed," says Mr Ryan.

"We have to sometimes gently remind customers that the only way these lights can benefit you is by shining in your eyes."

But photons and patisseries aren't everyone's cup of tea.

"Just coming through to pick up my coffee and sandwiches and having to pass all those cold glaring lights makes me more miserable than I was when I got up," said one theatre worker.