Patients with anti-LGI1 encephalitis often have sleep problems like insomnia or REM sleep behavior disorder (RBD), but studies systematically assessing sleep are lacking.

Patients recovering from anti-LGI1 encephalitis were invited to participate in a prospective observational single center study including comprehensive clinical and video-polysomnography (V-PSG) sleep assessment.

Twelve patients (50% male, median age 62 years, range 36-74) were included. In the acute stage, 8 patients reported insomnia, 1 had hypersomnia and 4 had symptoms suggestive of RBD. All patients received immunotherapy with intravenous steroids (n=11) and/or immunoglobulins (n=5), and 5 received additional rituximab. At study admission (median 211 days after disease-onset, IQR 141.5) 10 reported low-quality sleep, 7 had persistent insomnia (with difficulties to initiate and specially to maintain sleep), and 4 had additional daytime sleepiness. On V-PSG, sleep efficiency (time sleeping/time in bed) was below normality in 9 patients, with median 107.3 (IQR 82) minutes awake after sleep onset (WASO), distributed in many (median 2.5, IQR 5.3) WASO periods. One patient had RBD. Four patients had facio-brachial dystonic seizures (range 2-12) during V-PSG and 2 had epileptic focal non-motor seizures that had gone unnoticed by patients, relatives and treating physicians and improved after additional immunotherapy.