People with symptoms of SAD often experience 2 or 3 years of the condition before they are diagnosed.
First described in 1984 by Dr. Norman Rosenthal from the US, seasonal affective disorder (SAD), also known as seasonal adjustment disorder, is a form of depression that can occur at certain times of the year.
Mind, a UK organization that provides advice and support to individuals with mental health problems, notes that the majority of people with SAD experience the condition during winter months. Some people can be affected in reverse and experience depression during the summer months, but this is very rare.
According to Beth Murphy, head of information at Mind, the condition is often undiagnosed, making it difficult to know how many people suffer from the disorder. People with symptoms of SAD often experience 2 or 3 years of the condition before they are diagnosed.
However, Murphy says estimates show that around 10% of the population in Northern Europe experience milder symptoms of the condition, while 2% experience more severe symptoms.
According to the Cleveland Clinic, approximately 500,000 people in the US suffer from SAD, and around 10-20% of the US population suffer from milder forms of the disorders.
But regardless of the number of people worldwide who suffer from SAD, experts say that doctors appear to have lack of awareness of the condition.
Helen Hanson, chair of the Seasonal Affective Disorder Association (SADA) in the UK and a sufferer of SAD, told Medical News Today:"I would say that we are still finding that the medical profession don't seem to have sufficient awareness of the illness and particularly of its complexity. A pattern of presentation with depression needs to be noticed before a diagnosis can be made and general practitioners who do not have SAD on their agenda can still miss it completely.
So what are the signs of SAD to look out for?
Symptoms of SAD
According to Murphy, SAD can begin at any age. However, it is more likely to develop before the age of 21, and is twice as likely to develop in women than in men.
Other symptoms include:
Previous research has suggested that SAD may be caused by lack of light in winter seasons.
- Lack of energy for everyday tasks
- Weakened immune system
- Lack of concentration
- Overeating and weight gain
- Alcohol or drug abuse
- Feelings of guilt and worry
- Sleep problems
- Reduced libido
- Social and relationship problems.
Potential causes of SAD
It is unknown what the exact causes of SAD are, but previous research has suggested that since the condition occurs during the change in seasons, changes in light may trigger the disorder.
Murphy explains that when light hits the retina at the back of the eye, messages are sent to the hypothalamus - the part of the brain responsible for sleep, appetite, sex drive, temperature, mood and activity.
"If there's not enough light, these functions are likely to slow down and gradually stop," says Murphy, adding:
"Some people seem to need a lot more light than others for their body to function normally, and are therefore more likely to develop SAD symptoms when there are low levels of light."
It is thought that levels of serotonin - a neurotransmitter in the brain - may also play a part in the cause of SAD.
Low serotonin levels have been found in people who suffer from depression, particularly during winter months. This suggests that people with SAD may have an impairment in the brain's system that releases and absorbs serotonin.
Research has also found that people with SAD produce higher levels of the hormone melatonin in winter, compared with people who do not have the condition.
The pineal gland in the brain produces melatonin when we are exposed to darkness, which causes us to sleep. When it is light, the production of melatonin stops, making us wake up.
But Murphy says research has shown that melatonin is unlikely to be the only cause of SAD.
"We know that if someone with high melatonin levels is exposed to bright light, their melatonin levels drop to normal," she says. "However, trials have shown that even after their melatonin levels have returned to normal, most people continue to experience the depressive symptoms of SAD."
Previous studies have also shown that SAD could be caused by disruption to the body clock. It has been suggested that those with SAD may have a faulty body clock that is unable to set the body's circadian rhythm to daylight hours, causing tiredness and depressive symptoms.
Additionally, Murphy says reports have suggested that, like other forms of depression, SAD could be triggered by traumatic life events, physical illness, a change to diet or medication or use/withdrawal from drugs or alcohol.
'I couldn't make the connection to darkness and dull weather'
SADA's Helen Hanson first experienced symptoms of SAD at the age of 13. She had winter flu and felt depressed and anxious for many months.
Her doctor prescribed antidepressants, and she found she felt better as the summer months approached.
"I probably had sub-syndromal SAD, as did my mother, for most of my adult life. But it showed up as an inability to get up on winter mornings, a deep dislike of November and December and general feelings of despair which I did not recognise as seasonal," Hanson explains.
She explains that there were no recurring symptoms until she reached her late 30s, when she moved from a light modern flat to a dark Edwardian terraced house.
Hanson developed winter flu, which was followed by labyrinthitis - an inner ear infection. These conditions kept her at home for weeks, during which time she experienced sickness and dizziness.
"I developed a post-viral depression, which gradually got better, but its symptoms came back suddenly and unexpectedly the following September without any accompanying illness. I more or less came to a halt," she says.
For the next 3 years, Hanson attempted a series of self-help remedies to try and beat her depression, but these did not help. She says:
"I knew that I hated darkness and dull weather but didn't make the connection because I didn't know there was one.
Eventually, I saw a new doctor and she spotted a pattern. She pointed me towards SADA. I went to their annual general meeting and realised with huge relief that I was amongst fellow sufferers and that we all had something with a name. I was not mad after all."
Treatment for SAD
Hanson is now able to manage her SAD with a combination of antidepressants and bright light therapy (phototherapy).
Experts say bright light therapy has been shown to be 85% effective against SAD.
According to SADA, bright light therapy has been shown to be effective in up to 85% of diagnosed SAD cases.
The treatment involves exposure to artificial light from a light therapy box for an average of 2 hours each day. The light given off by the box mimics natural outdoor light and is at least 10 times the intensity of standard domestic lighting.
Experts believe light therapy works by regulating the brain chemicals linked to mood, therefore easing SAD symptoms.
The light boxes can be purchased for use at home, but Mind states that in some cases, more structured courses of light therapy that are supervised by a medical professional may be more beneficial.
However, Murphy told MNT that light therapy is not the only treatment for SAD:
"Talking treatments, such as counseling, psychotherapy or cognitive behavior therapy (CBT) can be extremely useful in helping people to cope with symptoms. Antidepressants may be prescribed for people with severe SAD and can be combined with light therapy for maximum effect."
Treatment does not necessarily have to involve outside interventions. Mind states that many SAD sufferers have found self-treatment options useful.
The organization recommends avoiding stressful situations, adopting healthy eating and exercise and trying to get as much exposure to natural light as possible during daylight hours.
But Murphy says it is important that people who are unable to manage symptoms of SAD or who find the symptoms are having an impact on their day-to-day life talk to their doctor about the condition.
"However, it is often difficult for people experiencing SAD to open up to health professionals so it's vital GPs are educated in early warning signs to look out for and the right way to approach the topic," she told MNT.
Doctors 'need better awareness' of SAD
Experts believe that there is not enough awareness surrounding SAD, which means many people may not know how to spot the symptoms, and many doctors may not know how to deal with a patient who is experiencing symptoms.
"SAD only ever appears as a footnote in information about depression, and we are concerned that the complexities of the illness don't get explored," said Hanson.
Mind is now calling for doctors to receive more training in all types of mental health problems.
"GPs should be able to give patients further information and discuss treatment options. It's important treatments are discussed regularly, particularly if symptoms worsen, or do not get better.
GPs should also make sure the patient feels included and listened to. If a GP feels this is outside their area of expertise, it might be worth referring to a psychiatrist."
Hanson told MNT that SADA believes there are now more male sufferers of SAD than originally thought, but males tend to be more reluctant to talk to their doctors.
"They self-medicate with alcohol or sink into deeper depression, with all that follows in terms of costs for the health service. GPs should look out for them particularly," she added.
'Lost connections with seasonality'
Many sufferers of SAD, such as Hanson, have learned to cope with the condition. But it is clear that coping with the symptoms of SAD and starting treatment for the condition begins with a visit to the doctor.
"Lots of people talk about the 'winter blues,' and many of us find the darkness and cold of December to February difficult. But if you find you have lots of the symptoms, they last longer than 2 weeks, and they are stopping you from living your normal life, you are likely to benefit from treatment for SAD," says Murphy.
Hanson notes that her experience has taught her that the world of artificial lighting in which we live today is an environment that some are unable to adapt to:
"We expect to live in the same way all year round under the same electric lighting. The world is now awake and artificially lit 24/7, and we have lost our connections with seasonality and the real rhythm of the days. For some of us, this is bad news."
Our Knowledge Centre article "Seasonal Affective Disorder: Causes, Symptoms and Treatment" provides more information on the condition.