There is a link for depression, but there again it tends to be a double edged sword and it goes in all directions. The people who have disruptions of their sleep can make their depression worse. For people who are depressed there is a tendency for their sleep to be modified and they will have more problems with insomnia. They will tend to have more frequent awakenings at night and find more difficult to either get asleep, initiate sleep or to maintain sleep. They wake up in the middle of the night open their eyes, looked around, start to get sleepy, go back to sleep and never even knew they were awake. And as far as your time during sleep is concerned it's of no consequence. For these people a lot of times they will wake up and they won't be able to go back to sleep. So they have a fragment type of sleep that is non-restorative. Analytically they will tend to have less of what we call slow wave sleep or deep sleep. They will have a tendency towards less of that and they will have a tendency toward more dream sleep with some of those dream sleeps being very vivid, very active or disturbing type dreams. For that they have those kinds of dreams states. The depression can affect the way you sleep hence the way you sleep can affect your depression and it can go in both directions.
