There's no getting around it. January can be bleak. The festive season is over, the evenings are cold and dark, and our bank balances are still recovering from Christmas.
You might be missing family who have returned home, or beating yourself up over failed New Year's resolutions.
There's even a day dedicated to the January blues. The third Monday of the month has been dubbed 'Blue Monday', the most depressing day of the year.
But if you've noticed you tend to feel particularly low during the winter months, you may be suffering from seasonal affective disorder or SAD, which is a type of depression. Fortunately, there are things you can do to feel like yourself again.
What causes winter depression?
The January blues are sometimes dismissed as being a myth. But there's plenty of scientific evidence to back up the idea that the seasons can affect our moods.
We don't know the exact cause of SAD, but one theory is that the lack of sunlight stops a part of our brain - the hypothalamus - working properly.
This can cause your body to produce too much melatonin, which makes you feel sleepy, and too little serotonin, which can affect your mood.
The hypothalamus also helps regulate our internal body clock. It's thought that fewer hours of daylight during the winter months can disrupt our internal circadian rhythm and contribute to low mood.
What are the symptoms of SAD?
The most common symptoms of SAD are a persistent low mood; a loss of pleasure or interest in normal everyday activities; feelings of despair; and feeling lethargic and sleepy during the day.
You may also find that you become irritable, sleep for longer than normal, and crave carbohydrates.
Some people will only experience a few mild symptoms of SAD. For others, the symptoms may be severe and can have a significant impact on their daily life.
If you suffer from SAD, you're likely to start getting symptoms between September and November. They may continue until March or April.
What can I do to make myself feel better?
You can't control the seasons. But there are things you can do to improve your mood.
You can begin with simple lifestyle measures. Try to get as much natural daylight as possible. Just going for a short walk every day or sitting near windows when you are indoors can make a difference.
Light therapy can also be helpful. It involves sitting by a special lamp, called a light box, for around thirty minutes every morning. This simulates exposure to sunlight, and encourages your brain to produce less melatonin and more serotonin. Light therapy is recommended by the NHS, and you can find out more about it on the NHS website.
If you're still struggling with the symptoms of SAD, it's worth visiting your GP. They may be able to recommend medication or a course of therapy to help boost your mood and get you feeling like yourself again.
Read more: Get help with heating costs this winter
Read more: Improve your circulation in 7 easy steps