NOCTURIA - A RARELY RECOGNIZED SYMPTOM OF SLEEP-APNEA AND OTHER OCCULT SLEEP DISORDERS

Background: Nocturia, awakening from sleep to urinate, is a common sym ptom in a variety of medical disorders and in the elderly. Awakening f rom sleep as a result of nocturia is thought to be secondary to a sens ation of urinary urgency resulting from an overextended bladder. Noctu ria-related awakenings cause significant sleep disruption and fatigue in elderly patients and are correlated with an increased number of fal ls at night. Sleep disorders such as sleep apnea are also common in th e elderly and are frequently the source of awakenings from sleep. The high incidence of both nocturia and sleep disorders in the elderly and other groups of patients suggests that sleep disorders may be the sou rce of some awakenings from sleep usually attributed by patients to no cturia. Nocturia secondary to sleep disorders would be causatively dif ferent from nocturia secondary to pressure to urinate in common medica l disorders and would require different diagnostic procedures and trea tment. Objective: To determine the frequency of nocturia as a symptom of primary sleep disorders. Methods: Eighty consecutive patients, 27 w omen and 53 men with a mean (+/-SD) age of 58.7 +/- 14.1 years, underg oing polysomnography (sleep study or PSG) for the evaluation of a susp ected sleep disorder and who met the sole criteria of awakening from s leep at least once and urinating voluntarily. Each patient had either a standard PSG recording or a PSG with administration of nasal continu ous positive airway pressure. Immediately after each episode of noctur ia during the PSG, patients were questioned about the reason they beli eved they had awakened. The PSG record immediately before awakening fr om sleep was then reviewed for potential causes of awakening. Patients were also asked on final morning awakening to fill in a questionnaire regarding their awakenings during the prior night. Patient reports we re compared with the PSG to determine the accuracy of subjective repor ts. Results: Patients awakened from sleep and voluntarily urinated a m ean (+/-SD) of 1.5 +/- 0.75 times per night for a total of 121 awakeni ngs for the group. The majority (79.3%) of these awakenings from sleep were found to be directly secondary to sleep apnea, snoring, or perio dic leg movements in sleep. Patients correctly identified the source o f their awakening from sleep on only five (4.9%) occasions and only on ce was sleep apnea correctly cited by a patient as a source of awakeni ng during the night. Conclusions: Most awakenings from sleep attribute d by our patients to pressure to urinate were instead a result of slee p disorders, particularly sleep apnea. The fact that patients do urina te once awake likely contributed to faulty post hoc reasoning and migh t have limited further inquiry by patients and their physicians in cli nical settings into the actual sources of awakening from sleep. Even i n those patients with well-known medical reasons for nocturia, sleep d isorders were still found to be the source of almost all awakenings fr om sleep. Patients were extremely poor judges of the reasons they awok e from sleep. The diagnosis of a sleep disorder should be seriously co nsidered whenever a patient reports frequent awakenings from sleep to urinate.