Under the weather: the biological basis for the January Blues


Every year the third Monday of January is labelled nationwide as ‘Blue Monday’, with it falling this year on 17th January. The day is supposedly the saddest day of the year due to a combination of factors including bad weather, darker days, and even failure to act upon New Year’s resolutions.

Although the evidence to support whether ‘Blue Monday’ is officially the saddest day of the year is limited, it does not take away from the fact that many people experience a drop in their mood and even seasonal depression throughout January. A popular term that many people choose to describe this feeling with is the ‘January Blues’.

It is often blamed on a variety of factors including the darker and colder days, and a return to normality after the excitement of the winter holiday period, however there are now many theories that demonstrate that the cause of the ‘January Blues’ has a strong biological basis.

Seasonal Affective Disorder, or SAD, is a type of situational depression most common during the winter months. It can often take time to diagnose as patterns in when symptoms occur need to be monitored over an extended period. There is a huge range of symptoms associated with SAD including persistent low moods, tiredness, and weight gain. SAD can occur at any time of the year; however, it tends to be more prevalent over the winter when the days are shorter.

Even though nearly 3 in 100 adults in the UK are thought to suffer from SAD, the exact cause of it cannot be explained completely. One of the most widely supported theories on the biological causes of SAD is that the shorter sunlight hours experienced throughout winter affect a person’s hypothalamus and leads to disruptions in hormone levels throughout the body.

Experts suggest that recognising the symptoms early and seeking help before they escalate is key to treating SAD

The hypothalamus is a part of the brain that is responsible for controlling the hormone system around the body, and a lack of sunlight can impact its function. The lack of sunlight results in disrupted levels of certain hormones being released by the hypothalamus, and this directly impacts the way that a person feels.

One such hormone is serotonin, a chemical neurotransmitter released by the hypothalamus that is thought to help regulate a person’s mood by relaying signals between nerve cells. A decrease in serotonin levels, influenced by a person’s lack of exposure to sunlight, will cause changes in the way a person feels and has often been linked to depression.

Another hormone involved in causing SAD is melatonin. This is produced by the brain in response to darkness and is heavily involved in controlling your body’s Circadian rhythm (internal body clock). Increased levels of melatonin lead to increased tiredness. Over the winter people tend to spend less time in the daylight, which influences the amount of melatonin that is produced. This explains why many people with SAD experience increased feelings of tiredness. The disruption to your body’s internal clock also means that key processes responsible for maintaining a person’s mental and physical health may not be performed as effectively, leading to further symptoms of SAD.

The symptoms of SAD can be very serious and should be addressed by a medical professional if a person is struggling to cope with them. Experts suggest that recognising the symptoms early and seeking help before they escalate is key to treating SAD. Many different treatments are available to help people manage SAD, with light therapy often suggested as a popular treatment method.

The treatment involves sitting in front of a specialist lightbox for between 30-60 minutes each day to try and decrease the amount of melatonin being produced by the body and regulate a person’s Circadian rhythm. Although its effectiveness is not yet widely acknowledged some people believe it helps treat symptoms in the short term and will reduce fatigue in a person suffering from SAD.

There are many resources available to help people suffering from SAD, and the NHS website contains lots of useful information for those wishing to find out more about the condition.

Image: Roan Lavery on Unsplash

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