The role of sleep in the pathophysiology of nocturnal enuresis.

Nocturnal enuresis (NE) is a common condition affecting 5-10% of all 7-year-old children. NE pathophysiology relies on three main factors, abnormal bladder function, excess urine production during sleep and the inability to awaken to the signals of a full bladder. The aim of this review is to evaluate the connection between sleep and its structure and the pathophysiology of NE. NE often occurs early at night and primarily in sleep stage 2 and "deep sleep". Although sleep stage distribution seems similar between NE and healthy children recent studies indicate differences in sleep microstructure. Several lines of research support the common notion among parents that children with NE are difficult to awaken. Moreover, children with NE and nocturnal polyuria differ in terms of hemodynamics and possibly autonomic activation at night compared to healthy controls and the hypothesis has formed that these changes are attributable to different sleep characteristics. In support of this hypothesis, children with NE often suffer sleep disordered breathing, as well as disturbed sleep due to awakenings and arousals. Periodic limb movements (PLM) have been seen in children with refractory enuresis but the clinical significance remains unclear.