Evidence suggests that the relationship between sleep problems and anxiety and depression is strong and goes both ways, reports the New York Times.

There is a definite link between lack of sleep and depression. In fact, experts say, one of the common signs of depression is insomnia, or an inability to fall and stay asleep.

While sleep requirements vary slightly from person to person, most healthy adults need between seven to nine hours of sleep per night to function at their best.

Sleep is where the body and mind is repaired, reordered and readied for the next day. Sleep restores hormones, skin cells, liver functions, heart health, and more.