A particular sleep profile runs in families and that the sleep profile seems to be fairly clearly associated with an increased susceptibility of family members to suffer from depression. Researchers may actually be closer to learning about the genetics of depression by pursuing sleep as a means of what might be underlying depression's development.
Two major sleep states are rapid eye movement (REM) and non-REM. Non-REM is classified by overall brain wave slowing. It occurs in stages 1-4, where 1 is the most activated brain and 4 is the least activated. Deep sleep is low wave, occurring in stages 3-4. REM is when brain activity is similar to when people are awake, but they are really deeply asleep.
The sleep profile the researchers identified is characterized by an earlier onset to this REM state and a drop out in slow wave sleep. Overall, there is more REM sleep and less slow wave sleep and a quicker slide into REM sleep. This discovery led the researchers to conclude that there is a fundamental regulatory problem in sleep which is linked to people's vulnerability for depression.
Relatives of depressed people who have rapid REM onset were four times more likely to also have rapid REM onset, and that their risk of depression was nearly double compared with the relatives of other depressed patients. The study findings also suggest that rapid REM onset indicates a higher risk of depression than having a family member with depression.
Most people are not aware that they may have this sleep profile. It is not associated with waking up often during the evening or not feeling rested in the morning. However, if people have a substantial number of family members who seem to have a problem with depression, that suggests they may have this sleep profile.
American Journal of Psychiatry (1998;155:192-199)
COMMENT: Disturbed sleep patterns are a very powerful indicator of depression. It is the most sensitive clue I have to recognize if I am getting depressed. Cardiovascular aerobic exercise is also one of the most effective treatments for disturbed sleeping patterns. Typically, 30-60 minutes four times a week. Doing this amount of exercise or even more is no guarantee that it will work. I know many depressed individuals who are exercise fanatics. However, it is one simple and inexpensive way to treat this problem.