Impact of growth hormone on central nervous activity, vigilance, and tiredness after short-term therapy in growth hormone-deficient adults.

Impairment of well-being and cognitive function has been reported in growth hormone-deficient adults, as well as an improvement of these parameters after GH substitution, albeit inconsistently. The effect of growth hormone on central nervous activity, vigilance and sleepiness was studied prospectively in 16 growth hormone-deficient adults (7 females, 9 males, mean age: 36.8 yrs) with multiple pituitary hormone deficiencies before and 3 months after the start of growth hormone substitution using two objective methods of measurement, pupillographic sleepiness test and a choice reaction time test. Significant differences were found for neither pupillary unrest index nor for reaction time, false or missing reactions in 12 evaluable patients (7 females, 5 males, mean age 37.8 years). Because of the known interrelationships between growth hormone, sleep and mood, the visual analogue scale for tiredness and standardized retrospective questionnaires regarding sleep and mood (Pittsburgh sleep quality index, Epworth sleepiness scale, Depression scale) were used as additional methods. After GH substitution, there was no difference in sleep efficiency and daytime sleepiness, but some of the subjective sleep parameters (sleep quality and sleep latency) improved significantly. There was a tendency for mood improvement, too. Although results must be interpreted cautiously due to the small sample size, we conclude that the improved sleep and mood parameters might be caused by other indices of general well-being in our study.