Many of us will miss the sunshine during the winter months and, even if you love the festive season, you may also look forward to the return of spring and summer. Some of us, however, are more affected by the change in daylight hours.
Seasonal Affective Disorder, or SAD, results in low mood and some of the symptoms of depression, including loss of concentration and motivation; social withdrawal; loss of pleasure in hobbies and interests; problems with going off to sleep and getting up in the morning; and waking up feeling exhausted the next morning. While SAD tends to mostly affect people in the winter months, a smaller number of people also experience the symptoms during the summer months.
What causes SAD? Certainly many people experience stress in response to pressures during the festive season. We know that pressure to spend money on food, presents and going out can be a financial burden which affects people’s need to feel financially secure into the New Year. People can also experience increased social isolation if they do not have families to spend the festive season with. On the other hand, if people are expected to be sociable or entertain others without a break, they can miss the need for privacy or time alone.
Any of these factors, if they prevent a person from meeting emotional needs can result in stress, which if not addressed, can give rise to anxiety or depression. But what about other potential causes of SAD?
One theory is that the change in sunlight disrupts the rhythm of our metabolism, rest and digestion, heart and breathing, sometimes called our body clock. However, this is not a cause of depression generally, so there is doubt that this theory can fully explain SAD.
An older idea suggests that the cause of SAD and depression are low levels of the brain chemical serotonin. However, this idea is no longer supported by the evidence. More recent research shows that antidepressants do not change levels of serotonin in the third of people who benefit from their use. Instead, they improve transmission of serotonin; although serotonin itself has not been shown to be the cause of depression.
A stronger candidate for the cause of SAD is the hormone melatonin. Melatonin is the hormone which induces the stage of sleep known as REM; the stage of sleep where most dreaming occurs, and which stands for rapid-eye movement.
People who have attended Suffolk Mind’s Suffolk’s Needs Met or Sleep Well, Work Well sessions will know that the quality of our sleep has a huge bearing on our mental health.
In particular, deep sleep, sometimes called non-REM or slow-wave sleep, is critically important for the repair of our body’s cells; and REM sleep, where most dreaming occurs, is involved in keeping our brains healthy, by discharging emotions we have not acted upon while awake.
We enter REM sleep at the beginning of sleep and, in a healthy sleep cycle have further episodes of REM sleep at ninety minute intervals, during the first half of the night. In the second half of the night, REM sleep episodes occur more frequently.
Short intervals of REM sleep calm emotions we have not acted on during wakefulness, and clean up neurotoxins which damage the brain’s cells. However, REM sleep also burns off the brain’s energy – so too much is not good for us. We have known for about fifty years now, that people experiencing depression have longer and more intense episodes of REM sleep.
The increased REM sleep experienced by people with depression is brought on by worrying about unmet emotional needs. In response to stress, worry and anxiety, too much REM sleep exhausts the brain; deprives us of deep sleep which repairs the body; and causes us to wake up feeling tired, miserable and lacking the motivation to address the problems which cause worry.
What has this got to do with melatonin and SAD? Well, melatonin is produced when it gets dark, so shorter days and longer nights would produce more melatonin and therefore increase the amount of REM sleep we have.
People with SAD have been found to have higher levels of melatonin than usual. It makes sense that people with higher melatonin levels would have more REM sleep than is healthy, and wake up feeling less rested and motivated to get going in the mornings.
While the symptoms of SAD may persist, even after melatonin levels have returned to normal in response to light levels, addressing causes of worry can help. Speaking to somebody who understands how we can meet emotional needs in healthy ways, is the way to lift symptoms – and our spirits during the festive season.