A reexamination of the relationship between growth hormone secretion and slow wave sleep using delta wave analysis.

Sleep onset growth hormone secretion is a reliable and reproducible finding in young adults and children. Secretion typically occurs during the first non-REM period of sleep and, despite some evidence to the contrary, growth hormone secretion has frequently been associated with the first period of slow wave sleep. By measuring delta wave activity (0.5-2 Hz) instead of slow wave sleep and, accounting for the within subject variability, it has not been possible to demonstrate a consistent or statistically significant linear relationship between delta wave activity and sleep-related growth hormone secretion. This suggests the presence of more complex mediating factors and the possibility that sleep onset and growth hormone secretion are two separate processes which are independently stimulated by events associated with sleep onset.

Prolactin secretion during sleep: a comparison between depressed patients and healthy control subjects.

Although several neuroendocrine abnormalities have been described in depressed patients, relatively little attention has been paid to the pattern of prolactin secretion during sleep. Sleep disturbances are frequently found in depressed patients, and the sleep electroencephalogram (EEG) typically shows significant changes in the first and last 100 min, when prolactin secretion frequently occurs. In this study, carefully defined inclusion criteria were used to ensure comparability in the quality of the sleep maintenance, so that the pattern of sleep-related prolactin secretion in a group of 26 depressed inpatients could be compared to that in a group of 20 healthy control subjects. Starting from sleep onset, the patients did not show any statistically significant difference in either the serum prolactin concentration or the pattern of integrated prolactin secretion relative to the control subjects. A statistically significant relationship between prolactin secretion and the REM-non-REM sleep cycle could not be demonstrated in these subjects.