Many of us experience seasonal variations in our mental health, particularly during the winter months associated with dark, cold days. Seasonal affective disorder (SAD) is a type of major depression that follows a seasonal pattern and is sometimes referred to as ‘winter depression’ [1, 2, 3]. SAD can interfere with all aspects of a person’s life, including relationships, work, social interactions and education, markedly affecting their quality of life. An individual suffering from SAD may experience feelings of sadness, hopelessness, stress and a lack of self-worth; these feelings can interfere with the person’s ability to carry out everyday tasks or participate in activities that they had previously enjoyed . A subsyndromal version of SAD in which individuals experience similar symptoms but of a mild nature is often referred to as the ‘winter blues’ [5, 6].
The names ‘winter depression’ and ‘winter blues’ refer to the fact that these symptoms most commonly occur during the winter months and start to improve during the spring. SAD that follows a winter pattern tends to cause symptoms such as low energy, hypersomnia (sleeping more than usual), overeating, weight gain, craving carbohydrates, and social withdrawal [1, 7]. SAD is thought to affect approximately 3 in every 100 people in the UK and more than 12 million people across Northern Europe [7, 8].
The exact cause of SAD is yet to be defined, although several risk factors for developing the condition have been identified. A major risk factor for developing SAD is an individual’s sex; females are four times more likely than males to be diagnosed with SAD. Geographical location is also an important risk factor, as SAD is most commonly diagnosed in countries with marked fluctuations in daylight and weather patterns across the seasons, such as those seen in England and Wales. Other risk factors include a family history of major depression or SAD, a current diagnosis of depression or bipolar disorder, and being of a younger age [9, 10].
Although several different hypotheses have been proposed to explain the development of SAD, there is not enough evidence to support any of these hypotheses to date . Currently, the main theory regarding the development of SAD relates to an individual’s exposure to sunlight [1, 9]. It is thought that the reduction in daylight or sunshine in the winter months may disrupt normal functioning of the hypothalamus  (a small area in the brain that plays an important role in the release of hormones and homeostasis ). This potential disruption is thought to have several effects on the body: levels of melatonin (a hormone produced by the pineal gland in the brain to induce sleepiness in response to reduced light) are increased and, at the same time, levels of serotonin (a hormone that works in the brain to regulate mood, sleep and appetite) are reduced. Alongside these changes, disruption to the functioning of the hypothalamus can, in turn, disrupt the body’s internal clock (circadian rhythm), which relies on sunlight to time various important bodily functions, such as the sleep–wake cycle. Together, these effects can lead to the characteristic symptoms of lethargy and low mood that are associated with SAD [1, 5, 11].
It is important that individuals who are suffering from symptoms of SAD see their GP. Although diagnosing SAD can be difficult, there are effective treatments available to help those with symptoms. A GP may carry out an assessment to evaluate an individual’s mental health, which may include questions covering mood; lifestyle; eating and sleeping patterns; seasonal changes in thoughts and behaviour; difficulty in performing daily tasks; and family or personal history of mental illness .
Treatment of SAD usually involves a combination of the following: light therapy; talking therapies such as cognitive behavioural therapy (CBT) or counselling; antidepressant medications such as selective serotonin reuptake inhibitors (SSRIs); and lifestyle measures such as taking regular exercise and developing methods to manage stress levels [1, 11].
Light therapy involves the use of a special lamp called a light box, which, typically, should be used for around 30 minutes to an hour a day in the morning. These lamps produce a very bright light and, as a result, can be used to simulate natural exposure to sunlight. It is thought that light therapy may help to relieve symptoms of SAD by stimulating the brain to reduce melatonin production and increase serotonin production. Light therapy has become a popular treatment choice for SAD and, in some individuals, can help to improve symptoms, including low mood [14, 8]. However, National Institute for Health and Care Excellence (NICE) guidelines advise that there is uncertain evidence for the efficacy of light therapy and suggest that treatment for SAD should be the same as that provided for other types of depression [14, 15].
Overall, the prognosis for SAD is usually good with the appropriate treatment. However, even with treatment, some individuals suffer from SAD throughout their lives [3, 7]. As we move into the cold, dark winter months in the UK, it is important that we take steps to look after not just our own mental health but also that of others. We should never be afraid to ask for help or to ask someone else if they need help
A mental health emergency should be taken as seriously as a physical one. You will not be wasting anyone’s time.
If you need help during a mental health crisis or emergency, NHS urgent mental health helplines provide:
- 24-hour advice and support – for you, your child, your parent or someone you care for
- Help to speak to a mental health professional
- An assessment to help decide on the best course of care
Please follow this link to find a local NHS urgent mental health helpline in England:
Call 999 or go to A&E now if:
- someone’s life is at risk – for example, they have seriously injured themselves or taken an overdose
- you do not feel you can keep yourself or someone else safe
Free listening services and support groups are also available:
These offer confidential advice from trained volunteers.
Call 116 123 to talk to Samaritans, or email: email@example.com for a reply within 24 hours
Text “SHOUT” to 85258 to contact the Shout Crisis Text Line. Or text “YM” if you’re under 19
Promotes the views and needs of people with mental health problems
Phone: 0300 123 3393 (Monday to Friday, 9am to 6pm)
The information in this article is not intended or implied to be a substitute for professional medical advice, diagnosis or treatment. All content is for general information purposes only. Always seek the guidance of your doctor or other qualified health professional with any questions you may have regarding your health or a medical condition.
Author: Rosalie Sykes, Medical Writer, Porterhouse Medical