Some people love the winter. Me - I wish I could hibernate for the winter. I am constantly tired, grumpy, hungry, and have to drag myself out of bet in the morning. I count down the days until the spring. I check the sunrise and sunset times, telling myself how much more daylight we'll have at the end of the week (14 minutes this week!). After some research, I've discovered I'm not alone, and there are loads of people who feel exactly the same.
Seasonal affective disorder (SAD) is a specific kind of depression that is related to daylight, therefore comes and goes with the seasons. It is sometimes called "winter depression", for obvious reasons. It affects more women than men, but is probably very under diagnosed. The classic symptoms of SAD are:
- low mood that you can't shake
- losing interest or enjoyment in normal life
- being irritable
- feelings of despair, guilt and worthlessness
- having no energy and feeling sleepy in the day time
- sleeping for longer than usual
- food cravings, especially for carbs, leading to increased weight
The exact cause isn't fully understood, but we know it's to do with the reduction in sunlight that happens in the autumn and winter months. It is important to remember that people evolved in Africa, near the equator, which has minimal differences in daylight length throughout the seasons. SAD may well be a result of the disruption of our body's natural internal clock (it's circadian rhythm). We have evolved to use sunlight to time various important functions, such as when we wake up, when we're most active, and when we sleep. This was very useful when we were evolving. It told us when the best time to hunt and gather food was, as well as when to find shelter to protect us from wild animals. Unfortunately, now we live in places where the daylight may not be strong enough to trigger these behaviours, or the day length is so short, while our minds might know it's morning and we need to get up, our bodies are not so sure!
How exactly the circadian rhythm is controlled is still unclear. One thing we do know, however, is that the lack of sunlight prevents a part of the brain, the hypothalamus, from working effectively. The hypothalamus regulates the production of melatonin, a hormone that makes you feel sleepy. In people with SAD it is thought that the body may be making too much melatonin, leading to the feelings of excessive sleepiness. The hypothalamus is also involved in the production of serotonin, a hormone vital for good mood, appetite regulation, and sleep. A lack of sunlight can lead to lower serotonin levels, which is strongly associated with depression.
The good news is that SAD can be managed. Have a chat with a GP if you think it is affecting you, and they'll be able to give you specific advice. Spending as much time outside in the daylight as you can, exercising, not sitting down for long periods of time, and managing stress can all help. If your SAD isn't too severe, ie it isn't totally ruining your life, the most common treatment is light therapy. This has been shown to be highly effective if done properly, with between 50 and 80% of users reporting complete remission of symptoms. Each light comes with its own instructions, but in general using them when you first wake up is recommended. SAD lights are widely available, and it is important to get the best one you can. When choosing a SAD light there are a few things you should consider. Traditionally white light therapy devices were the only ones with clinical data backing them up, however, in recent years a particular wavelength of blue light has also been shown to be effective. A SAD light must also emit at least 10,000 lux to treat SAD effectively and, as they are used to treat a medical problem, they are VAT exempt in the UK. I bought one for this winter, and I do think that (when I remember to use it), it makes a difference!
If none of this helps you, it's a really good idea to have a chat with a GP and tell them what is happening. There are second line therapies available, so help is out there!
Even though SAD is a real pain for those of us that suffer with it, I'm thankful I don't have the second type of seasonal effective disorder - summer depression. This is related to heat and humidity instead of light. While winter depression causes irritability and general grumpiness, summer depression can cause severe violence, so it could be worse!