AIM: To assess the actigraphy, an ambulatory and continuous monitoring of wrist motor activity fitted to study sleep/wake patterns in hepatic encephalopathy (HE).METHODS: Twenty-five cirrhotic patients (17 M, 8 F,mean age 56±11 years, 24/25 alcoholic, Child-Pugh A, B,C: 2, 6, 17) were included. The patients were classified into 3 groups: stage 0 group (n= 12), stage 1-2 group (n = 6), and stage 3-4 group (n = 7) of encephalopathy.Over three consecutive days, patients had clinical evaluation 3 times a day with psychometric test, venous ammoniemia, flash visually evoked potentials (VEP), electroencephalogram and continuous actigraphic monitoring for 3 d, providing 5 parameters: mesor, amplitude, acrophase, mean duration of activity (MDAI) and inactivity (MDII) intervals.RESULTS: Serum ammonia and VEP did not differ among the 3 groups. Electroencephalography mean dominant frequency (MDF) correlated significantly with clinical stages of HE (r= 0.65, P= 0.003). The best correlation with HE stage was provided by actigraphy especially with MDAI (r=0.7, P＜10-4) and mesor (r=0.65,P＜ 10-4). MDAI correlated significantly with MDF (r= 0.62,0.004) and was significantly shorter in case of HE compared to patients without HE (stage 0: 5.33±1.6 min;stage 1-2:3.28±1.4 min; stage 3-4:2.52±1.1 min;P＜0.05). Using a threshold of MDAI of less than 4.9min, sensitivity, specificity, positive predictive value, negative predictive value for HE diagnosis were 85%, 67%,73% and 80%, respectively.CONCLUSION: Actigraphy may be an objective method to identify HE, especially for early HE detection. Motor activity at the wrist correlates well with clinical stages of HE. MDAI and mesor are the most relevant parameters.