Is Your Depression a Sleep Disorder?
At some point in their lives most people have been deprived of sleep. For some it's a minor inconvenience that is quickly shrugged off and easily compensated for. Others find sleep deprivation harder to cope with. So, even in people without a pre-existing mood disorder, it quickly becomes clear that our experiences of sleep deprivation differ from person to person and vary according to circumstances. For example, a night of lost sleep through travel feels very different to a night of lost sleep through pain
The relationship between sleep disturbance and depression is well known, but complex and not fully understood. As much as sleep disturbances may be a consequence of depression they may also be a predictor and possibly even a cause. In terms of the predictive qualities, sleeping difficulties are a key marker for major depression in the five weeks prior to a depressive episode.
A good night of sleep helps to set us up for the challenges of the day ahead. But, once we deprive ourselves of sleep for more than 24 hours things start to change. We find it harder to make decisions and solve problems, our levels of irritation increase, and everything is just that bit more effortful. Our need for sleep is therefore critical to our mental and physical health, yet sleep disturbances are extremely common. In the case of people with major depression it is estimated that the vast majority have difficulties either falling to sleep, staying asleep or waking too early.
Sleep problems aren't restricted to adults of course and there is some evidence that depressive symptoms in children as young as eight may occur as a result of genetic factors (e.g. Gregory, 2009). However, by the age of 10 upwards, it seems that environmental factors are much more influential. It has been argued that treating sleep disturbances in early life may help to protect children from developing depression as adults, but that association isn't particularly clear. Like adults, children do need their quota of sleep, and poor sleep does seem to be associated with poor social skills development, low academic performance and attention.
Professor Matthew Walker has previously identified a neurological link between sleep deprivation, depression and anxiety. Centers in the brain associated with emotions are over 60 percent more active in people deprived of sleep. Walker describes the effects as the brain appearing to revert to primitive patterns of activity in that it is, "unable to put emotional experiences into context and produce controlled, appropriate responses." Such findings add to the speculation that, in some cases at least, depression may be less of a mood disorder and more of a sleep disorder. The fact that antidepressant medication suppresses what is known as REM (Rapid Eye Movement) sleep, may also be an important factor in reducing depression.
REM sleep can easily be monitored by the use of EEG equipment that records brain activity. People with major depression tend to have abnormal REM sleep patterns. The sleep cycle for people without depression follows a fairly predicable pattern and once asleep REM sleep begins after 1-2 hours. In people with depression, REM sleep often starts more quickly and lasts for longer. The more severe the symptoms the greater the eye activity and the longer the REM sleep. In people with major depression, a period of sleep deprivation actually has the effect of improving mood, suggesting a temporary effect of realigning the normal sleep pattern.
In this Sharepost I've only touched on a few of the issues that link depression to sleep disturbance. It will be interesting to see what emerges from future sleep research.
American Academy of Sleep Medicine (2009, February 1). Genetic Link Found Between Sleep Disorders And Depression In Young Children. ScienceDaily. Retrieved February 2, 2009, from http://www.sciencedaily.com /releases/2009/02/090201094127.htm
Yoo, S., Gujar, N., Hu, P., Jolesz, F.A., Walker, M.P. (2007) The human emotional brain without sleep - a prefrontal amygdala disconnect
Current Biology 17: 877-878