Objective: 

Aged individuals suffer deep sleep disturbances. Likewise, GH secretion stops in ageeing individuals. This report aims at rejuvenating sleep in old rats (24 months) through the chronic administration of exogenous GH.

Methods: 

Three groups of Wistar rats have been used: 1) Young controls, (12 animals, 90 days old) receiving two daily saline injections, 2) Old controls (12 animals, 24 months old) also received two daily saline injections 3: Old experimental group (12 animals, 24 months old) injected with two daily subcutaneous injections of GH (1mg/kg). After 30 days of treatment, all animals received chronic electrodes for conventional polysomnograpy and their sleep was recorded during 2h during light time. Digitized sleep EEG samples were submitted to the Fast Fourier Transform to analyze the power in delta, theta, alpha and beta power and the statistical differences between groups were analyzed.

Results: 

Old controls showed the typical age-related sleep impairments, but GH administration increased the NREM delta power in old experimental group up to levels with no difference from young controls. No changes were observed in alpha, theta and Beta EEG power. During REM, the EEG power increase was extended to the whole EEG range, from 0.5 to 30 Hz reaching levels without significant difference with those of young controls.

Conclusions: 

GH administered to old rats (24 months) rejuvenated the main EEG traits of sleep until reaching levels similar to those recorded in young (90 days) animals.