Longer nights, gloomy skies and less sunshine are well truly here in Britain and for many it can trigger low mood, sleepiness and spark cravings for comfort food. While many of us feel a bit lower in colder months, for some people these feelings can be particularly pointed and can be a sign of a condition known as seasonal affective disorder (SAD).SAD also known as ‘winter blues’ or ‘winter depression’, is thought to affect up to a third of British adults.Although the condition remains not fully understood by scientists it is believed to be caused by serotonin imbalances and disruptions to the body clock are believed to contribute. Unsurprisingly, regions with fewer hours of winter sunlight, like Scotland and Wales, report higher levels of SAD-related symptoms.But London a city which gets considerably more hours of sunshine than more norther climes was revealed to be one of the worst locations in England for developing symptoms associated with the disorder. Regions with fewer hours of winter sunlight, like Scotland and Wales, report higher levels of SAD-related symptoms, according to data from ONS and Met Office complied by lab test company York TestThe findings, complied by lab test company York Test, saw researchers examine data from the Met Office to find the average number of sunlight hours per UK region during the Winter months. They then combined this with Office for National Statistics data tracking rates of mental wellbeing in these regions using a 35-point scale as well as separate questionnaires and survey’s tracking specific issues like depression and anxiety. When this data was combined the team found Scotland as well as North and South Wales were the most susceptible to SAD.The fourth most susceptible was London followed by the South West in England ranking in fifth place. Experts said London may rank so highly due to its increased anxiety levels, which are recorded at 64.4 per cent — the highest of all the regions — making it a more stressful place to live in general. WHAT IS SEASONAL AFFECTIVE DISORDER (SAD) ? Seasonal affective disorder (SAD), also known as ‘winter blues’ or ‘winter depression’, is thought to affect as many as a third of British adults.It is a type of depression that comes and goes in a seasonal pattern. However, Some people with SAD may have symptoms during the summer and feel better during the winter.Symptoms of SAD can include: A persistent low mood A loss of pleasure or interest in normal everyday activities Irritability Feelings of despair, guilt and worthlessness Feeling lethargic (lacking in energy) and sleepy during the day Sleeping for longer than normal and finding it hard to get up in the morningCraving carbohydrates and gaining weight Difficulty concentrating Decreased sex driveSource: NHS  This is despite denizens of the capital enjoying 62 hours of sunshine on average a month in winter. That’s 21 more hours of sun than Scotland. In contrast, the least SAD susceptible places surveyed was the East and South East of England. The area with the lowest overall mental wellbeing score was the North east, with 24.84 per cent, in comparison to the East which had a score of 25.5 per cent. Psychologist and SAD sufferer Dr Pam Spurr spoke on BBC Radio London about the condition, describing it as a ‘rough ride’ for many people.She explained the disorder is caused by a biological imbalance of melatonin — a hormone that helps to regulate the body’s sleep-wake cycles — which gives you those symptoms of SAD, including tiredness, lethargy and low mood.’Sunlight switches off the production (of melatonin) naturally, so when you have decreasing sunlight in the autumn and winter, sufferers do not have their melatonin production diminished,’ she said in the radio show last autumn. She added that many sufferers also suffer with low serotonin — the chemical in the brain that can make you happy. But she explained that cities like London can make the symptoms of SAD, such as anxiety and low mood worse. ‘I think it is worsened when you are experiencing something like SAD and you are in a bustling city and you just feel isolated because you feel like you do not have the energy to get out there. You just feel like you want to hunker down and eat comfort food, which is another feature of it,’ Dr Spurr said. While the full mechanics of SAD are still not fully understood by scientists, the NHS explains the lack of sunlight in comparisons to summer can interfere with the body’s internal clock leading to its symptoms. The NHS explains the lack of sunlight can interfere with the body’s internal clock which can lead to symptoms of SADFor example, the body uses exposure to sunlight to time functions, such as waking up, so lower light levels in the morning put the body’s internal rhythm in conflict with your alarm clock.This is despite you waking up at the same time as you do in summer. Treatment for SAD includes lifestyle measures such as ensuring you getting natural sunlight, exercising and managing stress levels. The NHS also suggests using a light box — a very bright lamp which mimics outdoor light — and even taking anti-depressants and counselling. Dr Jon Van Niekerk, chair of general adult faculty at The Royal College of Psychiatrists, said SAD was a well observed issue during autumn and winter.’There are several things people can do to make themselves feel better if they suspect they might have SAD,’ he said. ‘This includes taking a walk during daylight hours, exercising regularly and talking to friends and family about how they’re feeling.’There’s a significant difference between feeling down and suffering from a mental illness such as depression. Anyone who thinks they might need professional help should reach out to their GP.’