Paradoxical sleep deprivation induces testicular damage and sperm dysfunction in rats: Protective role of recovery sleep and insight from SWE imaging

INTRODUCTION: Sleep deprivation is increasingly recognized as a potential risk factor for male infertility. Paradoxical sleep deprivation (PSD), corresponding to rapid eye movement (REM) sleep loss, has been shown to disrupt testicular function in experimental models. However, the in vivo structural consequences of PSD on the testis and the reversibility of such effects remain poorly defined. METHODS: A total of 22 male rats were randomly divided into three groups: PSD (96 h of paradoxical sleep deprivation, n = 6), RS (7-day recovery sleep following PSD, n = 6), and CTRL (control, n = 10). Testicular volume and stiffness were assessed bilaterally using high-resolution ultrasonography and shear wave elastography (SWE). Sperm parameters were evaluated by a computer-assisted semen analysis system. Histopathological changes were examined using hematoxylin-eosin (HE) staining and TUNEL assays. RESULTS: PSD rats exhibited significantly reduced testicular mean volume (1.37 ± 0.29 ml) and increased testicular mean stiffness (7.08 ± 1.23 kPa) compared to CTRL rats (1.9 ± 0.19 ml; 4.76 ± 0.72 kPa; both p < 0.05). Sperm motility, progressive motility, and morphologically normal sperm were markedly impaired in the PSD group. Histological analysis revealed seminiferous tubule atrophy, germ cell disorganization, and increased apoptosis. Following RS, testicular stiffness decreased (5.6 ± 0.59 kPa vs. PSD, p < 0.05) and sperm motility partially improved, although sperm morphology remained compromised. Significant negative correlations were observed between testicular stiffness and sperm motility metrics (r = -0.787 to -0.816, all p < 0.001). CONCLUSION: Paradoxical sleep deprivation induces substantial testicular structural and functional damage in rats. Recovery sleep exerts a partial restorative effect, especially on testicular elasticity and sperm motility. SWE may serve as a sensitive non-invasive tool for evaluating sleep-related testicular dysfunction, with potential implications for the management of male infertility.