Decrease in delta sleep in growth hormone deficiency assessed by a new power spectrum analysis

Seven pituitary dwarfs between 18 and 28 years old with congenital absence of growth hormone, i.e., isolated growth hormone deficiency (IGHD), were examined with polysomnography. Power spectrum analyses of the delta band showed a significant decrease in power in the delta sleep in the IGHD patients compared with the controls. Power spectrum analyses add a new dimension to the description of sleep, as it evaluates, not only frequency of the electroencephalogram (EEG) in time but also the amplitude of the EEG signal. This means that sleep of same quantity can have different powers; for example, 15 min of stage 4 in one person can have another quality than 15 min of stage 4 in another person. An additional observation was that the power in the delta band in the normal young controls showed a correlation to age, with significant decrease within a 10-year period.