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Cold nights, short days and low mood? Lets talk SAD

Cold nights, short days and low mood? Lets talk SAD

There’s a definite chill in the air, which together with shorter days inevitably means another step closer to winter.

While for some the prospect of merry festivities, snow (if we’re lucky) and warming hot chocolate on crisp cool days is quite enough to keep spirits up, for many the seasonal shift can signal a drop in mood. 

The association between colder, winter months and the way we feel is deeply embedded within the psyche of our popular culture today. Perhaps rightly so, there is something quite ominous about bleak skies, bare trees, dreary landscapes and darker days brought by mother nature and her seasonal change. As sociable beings we seem to acknowledge the need to cheer ourselves up when the world outside is cold and dark.  In fact, I recently came across a new fitness class intentionally designed to target those suffering with winter associated low mood by recreating the sounds, sights and touch of summer in a 30 minute ‘experience’. What really caught my interest though was something I read about a few years ago - a light emitting ear plug (of all things) that claims to boost your mood when hours of natural daylight are reduced (more on this later…)

Seasonal Affective Disorder, or SAD as it’s commonly known is a mental health condition thought to affect approximately 3% of the population . Some refer to it as a ‘winter depression’ and key to its diagnosis is the seasonal pattern associated with it. People suffering with SAD often notice a persistent low mood during autumn and winter accompanied by a loss of pleasure or interest in everyday activities and a significant lack of energy. These features are also seen in other forms of depression, and together with the seasonal variation what also helps identify SAD are the changes in sleep and appetite. 

Typically individuals suffering with SAD find they sleep for longer than normal and find it particularly difficult to get up first thing in the morning. Some experience increased hunger or appetite for food, especially carbohydrate rich products which can lead to weight gain. In its most severe form people can become severely ill and require admission to hospital.

What causes SAD?

We don’t know exactly what causes SAD; there is a genetic or inherited component, though most research has focussed on changes in our exposure to daylight and darkness. 

We all possess a natural 24 hour body clock located deep within the brain, responsible for the regularity of our sleep-wake cycle. This biological clock is dependent on its ability to detect changes in daylight. Sunlight in particular stimulates this part of our brain to produce changes which decrease the production of a chemical called melatonin. 

You might have heard of melatonin before but in essence it’s a hormone produced by part of the brain called the pineal gland. It’s main job is to tell our body clock what time it is by detecting day length. When its daytime, melatonin levels are low and when it’s night levels are high. This helps our body know when its time to wind down at the end of the day but also when to rise and shine in the morning. 

In SAD it’s thought that melatonin levels rise later in the night and remain high in the day for longer, possibly producing a greater sense of sleepiness and fatigue than in those who don’t have the condition. 

On its own however changes in melatonin don’t seem to account for the full story. Studies have also found another chemical in the body, serotonin, may have a role to play. Serotonin has a well known and well researched association with mood balance and is also involved in the production of melatonin. In fact the medications used to treat moderate and severe episodes of depression work by boosting serotonin levels in the brain and for some people with SAD these mediations are very effective. While the exact mechanism of serotonin involvement isn’t entirely clear there is early evidence suggesting it may be to do with a reduction in the amount of free and available serotonin in the brains of people with seasonal affective disorder, due to the presence of too much protein that removes it. 


Treatments for SAD vary, though depending on the severity of symptoms options can include talking therapy (cognitive behavioural therapy aka CBT), medications such as antidepressants and unique to seasonal associated low mood, light therapy.

In its most common form it requires a person to sit by a special lamp ingeniously termed a 'lamp box’ for approximately 30 minutes to an hour every morning. The idea is to simulate the sunlight that’s missing during darker winter months and one theory is that the light may help your brain reduce the production of melatonin, increasing instead the production of serotonin. 

Light boxes aside, does it actually work? 

Well, the answer is not as straightforward as we might hope. While many people report a vast improvement in their symptoms, the studies done to investigate it don’t always agree. In fact the studies done to investigate it don’t always agree with each other! To really figure out the effect of a treatment, we need to know how well it works when exposing a really large group of people to it. Some studies have done this and have found some improvement in symptoms, however the beneficial effects are much less obvious when you apply the strictly controlled conditions that are needed to truly assess an overall effect. It doesn’t really help that a lot of the studies that do report positive findings have been somewhat limited by their study design- a bit like a piece of evidence not holding up in court. That said, when you think about it, the challenges here are pretty obvious. Imagine trying to create a placebo for a giant bright light! 

It’s interesting that you can’t access a light box on the NHS and perhaps this is part of the reason why. Sometimes your doctor may suggest investing in one yourself if you experience symptoms given there isn’t any more conclusive guidance, so it becomes a matter of personal preference.  

Remember the light emitting ear plug? 

Well there’s a company out there that manufactures an ear plug that emits light and reportedly improves symptoms of low mood particularly those associated with SAD.

In essence it looks like an iPod. It comes with a handheld component, and two headphones that you plug into each ear. The handheld device ‘emits’ the light into your ear canals and supposedly reaches your brain where it somehow improves your mood. 

The company does do a good job at superficially guiding you along the route of thinking this is all very evidence based, and even has an entire section of its website dedicated to ‘evidence’. They also tell a nice story which goes along the following lines: A few years ago a team of researchers discovered that in addition to the eyes, other areas of the human brain are sensitive to light. In fact the same proteins in the eyes are also found in other parts of the brain and so the company concluded that this must mean shining a light through the ear canal is a genius idea and would help improve mood. 

Or does it?

I took a look at their cited ‘evidence’ and found that actually a large number of quoted studies did their experiments on mice which clearly are very different to humans. Other studies they cite didn’t even look at the effect of such transcranial light on SAD symptoms in the first place, but instead looked at the effect of it on the speed of athletes (i’m confused). Another study experimented by shining bright light through the ear canals of deceased cadavers…and the one study that did suggest some promise initially, on further reading didn’t include a placebo or controlled condition and had a very short follow up period- so there’s no way of knowing if the effects were at all long-lasting! 

Perhaps there is more to transcranial light and it’s impact on mood, but there really isn’t enough evidence to suggest purchasing products like this, at least not yet.

If you think you are experiencing symptoms of SAD or any other form of depression, then please seek the advice of your GP. 

Front Cover- Samuel Zeller, 2017

Front Cover- Samuel Zeller, 2017