Abstract: We included four studies with 149 randomized participants. We identified two studies awaiting classification for which we were unable to assess eligibility and one ongoing study. Participants differed in severity of illness as assessed by APACHE II scores in three studies and further differences existed between comparisons and methods. One study compared propofol versus no agent, one study compared different doses of propofol and two studies compared propofol versus a benzodiazepine (flunitrazepam, one study; midazolam, one study). All studies reported randomization and allocation concealment inadequately. We judged all studies to have high risk of performance bias from personnel who were unblinded. We noted that some study authors had blinded study outcome assessors and participants for relevant outcomes. It was not appropriate to combine data owing to high levels of methodological heterogeneity. One study comparing propofol with no agent (13 participants) measured quantity and quality of sleep using polysomnography; study authors reported no evidence of a difference in duration of sleep or sleep efficiency, and reported disruption to usual REM (rapid eye movement sleep) with propofol. One study comparing different doses of propofol (30 participants) measured quantity and quality of sleep by personnel using the Ramsay Sedation Scale; study authors reported that more participants who were given a higher dose of propofol had a successful diurnal rhythm, and achieved a greater sedation rhythmicity. Two studies comparing propofol with a different agent (106 participants) measured quantity and quality of sleep using the Pittsburgh Sleep Diary and the Hospital Anxiety and Depression Scale; one study reported fewer awakenings of reduced duration with propofol, and similar total sleep time between groups, and one study reported no evidence of a difference in sleep quality. One study comparing propofol with another agent (66 participants) measured quantity and quality of sleep with the Bispectral Index and reported longer time in deep sleep, with fewer arousals. One study comparing propofol with another agent (40 participants) reported higher levels of anxiety and depression in both groups, and no evidence of a difference when participants were given propofol. No studies reported adverse events. We used the GRADE approach to downgrade the certainty of the evidence for each outcome to very low. We identified sparse data with few participants, and methodological differences in study designs and comparative agents introduced inconsistency, and we noted that measurement tools were imprecise or not valid for purpose. We found insufficient evidence to determine whether administration of propofol would improve the quality and quantity of sleep in adults in the ICU. We noted differences in study designs, methodology, comparative agents and illness severity amongst study participants. We did not pool data and we used the GRADE approach to downgrade the certainty of our evidence to very low.

Plain-language summary: The evidence is current to October 2017. We included four randomized controlled studies (clinical studies where people are randomly put into one of two or more treatment groups) with 149 participants in the review. Two studies are awaiting classification (because we could not assess their eligibility) and one study is ongoing. All participants were critically ill and were in the ICU. We did not combine the results from the studies because of differences in comparison (called control) treatments and study design. One study compared propofol with no agent. This study used polysomnography (which records brain waves, oxygen level in blood, heart rate, breathing, and eye and leg movements) to measure sleep quality and quantity. It reported no improvement in duration of sleep with propofol but participants woke up less often and for shorter lengths of time and described their sleep quality as being improved with propofol. One study compared a higher dose of propofol at night described as additional night sedation, with a constant day-time and night-time dose. This study used the Ramsay Sedation Scale (which is normally used by anaesthetists to assess how easily a person is roused) and reported that participants appeared to have an improved sleep rhythm. Two studies compared propofol with benzodiazepines (a tranquilizing medicine; flunitrazepam in one study and midazolam in one study). These studies used the Pittsburgh Sleep Diary and the Hospital Anxiety and Depression Scale to measure quantity and quality of sleep. The study with flunitrazepam reported fewer awakenings of reduced duration with propofol but similar total sleep time in each group and the study with midazolam reported no difference in sleep quality. The study with flunitrazepam also measured sleep with Bispectral Index (used by anaesthetists to assess depth of anaesthesia) and reported longer time in deep sleep, with fewer awakenings. The study with midazolam reported higher levels of anxiety and depression in both groups, and no difference when participants were given propofol. No study reported on side effects. We judged the evidence to be very low quality. We found only four small randomized controlled studies and the results of the studies were not consistent. We noted differences in illness severity of participants and the medicines that were compared with propofol in the included studies. Measuring quality of sleep using diaries, questionnaires and scoring systems is based on, or is influenced by, personal feelings or opinions, and we were concerned that staff and participants were aware which medicine they had been given; we believed that this could have influenced the results. Only one study used polysomnography, which is the most appropriate unbiased measurement tool for sleep. We were unable to collect sufficient evidence to determine whether propofol given at night to adults in the ICU improves quality and quantity of their sleep, as a way of helping recovery.