[Effect of growth hormone on sleep energy]

The purpose of the study was to examine REM and delta sleep energy in adults with high and normal plasma growth hormone (GH) concentration by means of power spectrum EEG analysis. After a three-day regular sleep/waking schedule, all-night polysomnographic recordings were performed on two consecutive nights before as well as one year after treatment for acromegaly by adenomectomy. The sleep energy was calculated by power spectrum analysis. We studied nine patients aged 24-45 years with untreated active acromegaly. The same patients were re-examined one year after adenomectomy when plasma GH concentrations were normal. The acromegaly was verified biochemically by measuring basal plasma GH concentration and plasma GH during hyperglycaemia as well as insulin-like growth factor. Cerebral computer tomography (CT) and magnetic resonance (MR) scans revealed an intrasellar adenoma in all patients. The resulting sleep records obtained before and after adenomectomy were subjected to power spectrum analysis and a manually blinded sleep scoring. The power spectrum analysis showed that when circulating GH was elevated the energy in the REM sleep per minute was significantly higher compared to the REM energy/min after surgery when GH concentrations had normalized. A similar relation was found for delta sleep (stage three and four, deep sleep) where the energy per minute was higher before treatment than after. The study demonstrates that plasma GH concentration was correlated to sleep energy. During high GH concentration the REM and delta sleep energies were high and normalization of plasma GH was followed by normalization of REM and delta sleep energy per time unit.