Obstructive sleep apnea (OSA) can occur exclusively during rapid eye movement (REM) sleep, but its frequency and significance are unknown. Furthermore, REM sleep suppression is common in adults with sleep apnea and the total amount of REM sleep on the first night in the sleep laboratory is usually reduced. We intended to study the frequency of this entity and its effect on daytime hypersomnolence.
We retrospectively reviewed the Polysomnograms and the multiple sleep latency test (MSLT) of 140 consecutive patients diagnosed with OSA [apnea hypopnea index (AHI) ≥ 5]; The nonREM-AHI, the REM-AHI and the mean sleep latency (MSL) were noted for each patient. The combination of a nonREM-AHI ≤ 6 and a REM-AHI ≥ 15 was considered diagnostic of REM specific OSA. An MSL < 10 was considered to be indicative of significant daytime hypersomnolence. The MSL of the REM-specific OSA group was compared to the MSL of a non-REM specific OSA group (n=16) within the same range of AHI and Arousal Index (AI) using Chi Square Test.
18 patients (12.8%) had exclusively REM-specific OSA. Their AHI ranged from 5 to 21 with a mean of 10.5±5.0. Ninety one patients (65%) had an MSLT. Eleven patients of these had REM-specific OSA. The mean MSL of the REM-specific OSA group and the matching group were 6.2±3.9 and 8.3±5.9 respectively. 91 % of the REM-specific OSA group and 56% of the matching group had an MSL < 10 (p=0.131).
REM sleep-related OSA is found in about 13 % of patients with OSA. Almost all of these patients had significant daytime hypersomnolence. There was a trend for this group to have more daytime sleepiness than a group of patients with OSA of the same severity.
Since some patients have OSA exclusively during REM sleep, the diagnosis of OSA should not be excluded unless the patient has REM sleep on the polysomnography.
Z.C. Boujaoude, None.