Jessica LawrenceBBC News NI

BBC A close-up image of Cherry Cantrell sitting at the desk in her office. She is an older woman, with a purple hue in her short hair. She is wearing apair of circular glasses, a silver necklace, as well as a purple lace top and black waistcoat. She has a yellow 'Aware NI' pin on her lapel. She is looking at the camera and smiling. Behind her are posters and lights on the wall of her office, but they are blurred.BBC

Cherry Cantrell, from the mental health charity Advice NI, has been using a colleague’s old Sad lamp for the past decade to help ease her symptoms

When the trees start to lose their leaves and the “lovely colours of autumn” disappear, Cherry Cantrell begins an almost six-month battle to fight off the so-called “winter blues”.

She has Seasonal Affective Disorder (Sad), a type of depression which is thought to be brought about by a lack of exposure to sunlight.

“At this time of year, I find that things that normally wouldn’t annoy me about my family, my dog, my friends [do]… I feel really irritable, just annoyed at everybody and everything,” she said.

For the past 10 years, Ms Cantrell has been using a Sad lamp, or a light therapy box, as a way to lift her spirits during the shorter days and longer nights, and return to a version of herself she recognises.

The Royal College of Psychiatrists said in the UK about three in every 100 people have significant winter depression.

‘Nobody gets how I feel’

Winter, Ms Cantrell said, brings about many of the symptoms of depression – a lingering low mood, losing interest in things you love, sleeping for longer than normal – that she normally wouldn’t experience during the rest of the year.

“The worst thing I suppose is just the impact it has on my relationships generally,” she added.

“I just feel nobody really gets it and so I feel quite isolated, and if I do try to explain it and somebody tries to solve it for me, then I get even more agitated and angry with them.

“It’s just that darkness, that lack of sunlight and all of those things that I do to keep myself well, I really struggle to keep those things going in my life.”

When she feels her mood begin to drop, Ms Cantrell brings out her lamp – a small box which is supposed to mimic sunlight – and uses it during her work day.

Cherry Cantrell holds a small, white light box in her hand as she sits at her desk. She is looking at the camera with a neutral expression on her face. She has short hair with a purple hue and is wearing a purple lace top and a black waistcoat. In front of her is a desktop computer.

The small device has made a big difference in Ms Cantrell’s life

According to the NHS, it is thought the light may improve Sad by encouraging your brain to reduce the production of the hormone melatonin, which causes sleepiness, and increase the production of serotonin, a hormone that affects mood.

While Ms Cantrell said she has noticed a difference to her mood after using the light.

“It’s a very subtle change for me,” she added.

“What I notice is it’s almost like it’s taken an edge off those extreme reactions to things that are happening.”

Ms Cantrell, who works as a support services officer at the mental health charity Aware NI, urged people who might be experiencing the symptoms of Sad to contact their GP, watching what they eat, connecting with loved ones or even getting outside during the day.

“Even if it’s grey, there’s light there, there’s natural light there, go out and get some,” she added.

Sad lamps in NI libraries

Since introducing Sad lamps into some rural libraries five years ago, Libraries NI have now introduced at least one in every library across Northern Ireland.

Library members can also borrow a lamp for up to three weeks for free.

A close-up image of Paul Kelly. He is a young man, with short, dark hair and a dark beard with some patches of grey. He is smiling at the camera. He is wearing a pair of circular black glasses. He is wearing a light blue shirt. He is standing in front of shelves of books, but they are blurred.

Paul Kelly from Libraries NI said the Sad lamp borrowing initiative has been well received

Paul Kelly, the organisation’s senior service manager, said the benefits of the lamp are two-fold.

“For Libraries NI, we are a welcoming, neutral space and the Sad lamps offer people that opportunity to benefit from the lamps while they’re reading, taking part in knit and natter activities and just enjoying the library space,” he said.

“So it’s important for us to have that service available for the customers.”

A still image of a Sad lamp sat next to a plastic box containing leaflets about the Sad lightbox. The lamp is an A4-size white light, which is turned off. It is placed on a wooden desk, with the bottom of a small Christmas tree in the distance.

There is a Sad light box in every public library across Northern Ireland, with some available to borrow

Mr Kelly said the borrowing programme was proving extremely popular, particularly with younger people, with most of the loanable lamps out of stock.

While they can’t claim that there are health benefits, Mr Kelly said Libraries NI were hearing good things from those who have borrowed the lamps.

“We’re happy people receive the benefit of it, and if in doing so we have more people coming through the doors that’s excellent,” he added.

What is Seasonal Affective Disorder?

Seasonal Affective Disorder is a type of depression that comes around seasonally, but some may also experience Sad during the summer months.

The exact cause is not fully understood, but it is thought to be brought on by shorter days due to a reduced exposure to sunlight.

It’s believed the lack of sunlight stops a part of the brain called the hypothalamus from working properly, affecting the production of melatonin, seratonin and the body’s internal clock – or circadian rhythm.

Getty Images A stock image of a young person turning on a Sad lamp on their desk. He is sitting in an office chair and is turned away from the camera, with one finger on the lamp. He is wearing a white and red raglan shirt. He is sitting in front of blue patterned wallpaper.Getty Images

People are advised to use a Sad lamp for about 30 minutes a day

Symptoms of Sad can include: a persistent low mood, irritability or feeling lethargic during the day.

Sufferers can also have feelings of despair, guilt and worthlessness, have difficulty concentrating and a decreased sex drive.

The NHS said the main treatments are lifestyle measures, like exercising regularly, talking therapies or light therapy like light boxes.