MOST of us feel like hibernating when the days get darker and shorter.

But for some people, the misery of winter is an annual nightmare that brings lethargy, anti-sociability and depression.

Actor Johnny Briggs, who plays Mike Baldwin in TV soap Coronation Street, is one of the estimated half a million Seasonal Affective Disorder (SAD) sufferers in Britain.

SAD is thought to be caused by biochemical changes in the body due to lack of daylight.

It is more common in women than men, and increases with distance from the equator - except where there is snow on the ground.

Evening Press feature writer Natalya Wilson, 31, has felt the effects of SAD every winter for at least six years.

"You can be the most upbeat person most of the time, but for three months of the year you can be the most miserable," said Natalya.

"It's affected by the light, so if you get a sunny day you can feel really great, but days where there's no light can make you feel really depressed and lethargic.

"Sometimes you don't even want to leave the house.

"I can sometimes feel it around November, but there's usually so much to think about that it's not until January that it really starts to affect me.

"I'm happy in my job and my personal life, it's just January to March that I feel this way."

Natalya has seen doctors about the condition, but now prefers to deal with her symptoms holistically.

"If we get a nice sunny day I try to go out and make the most of it, so the feeling lasts a bit longer, and so I don't feel as down and as though I'm staying in all winter.

"I get plenty of exercise and fresh air, and if we get a rubbish day I get out of the house and do something outdoors so it doesn't manifest itself and make me feel worse."

York GP David Geddes said he saw many patients affected by winter and shorter days.

"To diagnose SAD you've got to spot a reoccurring pattern," he said.

"You won't know necessarily when you first start to suffer, but when you're still suffering the same symptoms at the same time of year three years on, recognising the symptoms in October and November and feeling buoyant and back to normal in spring, it could be SAD.

"The most important thing, although we don't fully understand what causes SAD, is that it is associated with a reduced amount of sun exposure which reduces the brain chemical serotonin.

"That gives you classical symptoms of low mood. It differs a bit from depression in that people with depression don't tend to sleep well, but people with SAD sleep more.

"People with depression lose their appetite, but people with SAD get more appetite, particularly a carbohydrate craving."

Dr Geddes said some people responded positively to light therapy.

"Light therapy can improve symptoms in two in three people.

"It is not a cure and you need to keep on using it.

"Light therapy usually starts in autumn and you need to be about two to three feet away from the light bulb for 30 to 40 minutes a day - preferably first thing in the morning.

"Some people suffer side-effects such as nausea and some people can't get to sleep if they use it at night.

"You feel an appreciable benefit after about a week of ongoing treatment.

"The key message is that an ordinary light bulb is not strong enough and sun beds don't help because sun beds use UV light and you can't get the strength of light you need.

"Natural sunlight even on an overcast day can help. Going for a walk outside for one or two hours a day may ease symptoms.

"Try and maximise your exposure to it."

For general information on SAD contact the Seasonal Affective Disorder Association at www.sada.org.uk.

:: Symptoms

Oversleeping but not feeling refreshed

Overeating and carbohydrate craving

Depression

Avoiding company, irritability

Joint pain or stomach problems and lowered resistance to infection

:: Treatments

Light Therapy

Food - pulses, white meat, dairy products and fish. Eat little and often and drink plenty of fluids

St John's Wort is often used to combat winter blues. Always check with your GP that it will not affect any other medication

:: Top tips

Take regular exercise to boost energy levels, lift depression and maintain a healthy weight

Get up early as lying in bed will make you feel more tired

Keep warm

Updated: 11:19 Friday, January 13, 2006