Sleep and circadian abnormalities in patients with cirrhosis: features of delayed sleep phase syndrome?

Sleep disturbances are common in patients with cirrhosis but their origins are unknown. The aim of this study was to investigate possible involvement of the circadian system. Sleep was monitored for two weeks, in the home environment, using sleep diaries and actigraphy, in 35 patients with cirrhosis (21 men; mean age [+/- 1SD] 58 +/- 10 yr) and 12 matched healthy controls (eight men; mean age 56 +/- 15 yr); urinary 6-sulphatoxymelatonin (aMT6s), the major metabolite of melatonin, was measured over 56 h, to assess circadian rhythmicity. The patients woke up and got up significantly later than the healthy volunteers and their sleep was significantly more fragmented. Mean 24-hour urinary aMT6s outputs were comparable in the patients and controls (15.5 +/- 13.1 vs. 20.3 +/- 13.8 mu g/24 h) but were significantly lower in the decompensated patients (9.8 +/- 11.3 vs. 17.0 +/- 13.3 mu g/24 h; p=0.03). Significant 24-hour urinary aMT6s rhythms were observed in 26 (79%) of the 33 patients with complete urine collections; 20 patients had a normally timed (midnight-06:00) urinary aMT6s peak, while it was delayed (>= 06:00) in the remainder. Significant correlations were observed between abnormalities in the urinary aMT6s profile (delays and/or lack of a 24-hour rhythm) and indices of sleep timing; parallel delays were observed in sleep habits and urinary aMT6s peaks. The association between delayed circadian rhythms and delayed sleep habits observed in approximately one-third of the patients with cirrhosis is reminiscent of 'delayed sleep phase syndrome'; this condition is managed by attempting to resynchronise the circadian clock by exposure to bright light shortly after morning awakening.