Dr Ernest Hartmann carried out studies in connection with people who have stable sleep patterns. His aim was to define whether waking events influenced people’s need for sleep.
For instance, a loss of boyfriend or stress caused many young women to have an increased need for sleep. Some people who had undergone successful psychotherapy for their emotional difficulties, and some meditators, found their sleep need was decreased.
Wanting to know more about why these situations changed sleep need, Hartmann went on to study dream sleep in a group of women who suffered premenstrual tension (PMT). This group were prone to depression and irritability during PMT—records show there is an unusually high rate of murder, suicide and admission to psychiatric hospitals during this time. Although Hartmann found this group needed a little more sleep time than a control group, the main feature of change was their increased need for dreaming. Their length of time spent in dreaming increased in relationship to their depression.
The conclusion reached was that one of the functions of dreaming is to help deal with difficult states of emotion or anxiety.