sleep and depression

Sleep still is one of the greatest biological mysteries. After many decades of research, we know all about what causes us to feel sleepy, different types of sleep, electrical activity in our brains while we sleep, and the mechanisms of waking up after sleep, but we still don’t know why we sleep.

It is clear we do need regular and normal sleep for our overall health. It has persisted during evolution. All animals have some form of sleep, so far as researchers have been able to test. Sleep is strictly regulated. Sleep loss is inevitably followed by a rebound.

The relationship between memory and sleep is one of the most evident. Many studies have shown that while sleeping the brain is busy consolidating memories. The neurons in rat brains firing while learning a new task are active exactly the same way during the following sleep period, as if to imprint the path necessary for performing the task. The simultaneous reactivation of coherent memory traces takes place in the hippocampus and in the neocortex.

Clear evidence exists for a strong link between mood and sleep, not in the least because in most cases symptoms of depression are felt most intensely in the morning after waking up. Individuals with mild episodic depression and seasonal affective disorder have lower than normal melatonin levels. People who suffer from major depression or panic disorder also have low levels of melatonin clinical studies have shown. Administration of melatonin, which possibly causes a surge in seratonin levels, may help alleviate the symptoms of depression. It may also improve sleep patterns in patients with depression. Further studies are necessary to confirm this.