There is a close relationship between depression and sleep deprivation. Sleep disorders such as insomnia, sleep apnea and delayed sleep phase syndrome rob you of sleep. Lack of sleep saps your energy, makes you irritable and sucks all the joy from your life. The result? Decreased productivity and an increased risk of mistakes or accidents can cost your employer hundreds of dollars. You could even lose your job because of it. Yet another reason for depression.

Insomnia disrupts the normal way of life. This can become a vicious circle. You have insomnia. You worry because you can't sleep. As the worry increases, your insomnia escalates. Leading to what? Again, depression. If you are already depressed, then the depression deepens. If you are recovering from depression, insomnia can cause a relapse.

The Science Blog tells us:

Two new studies show that insomnia, far from being a symptom or side effect of depression, may instead precede it, making some patients more likely to become and remain mentally ill.

The article continues with this quote:

"The new findings are especially significant because they suggest that targeted treatment for insomnia will increase the likelihood and speed of recovery from depression," said Michael Perlis, Ph.D., director of the University of Rochester Sleep and Neurophysiology Research Laboratory (URSNRL),

If you're suffering from depression and you aren't sleeping well, perhaps sleep deprivation is causing your depression.