Sleep disorders are common in the general population and even more so in clinical practice, yet are relatively poorly understood by doctors and other health care practitioners. These British Association for Psychopharmacology guidelines are designed to address this problem by providing an accessible up-to-date and evidence-based outline of the major issues, especially those relating to reliable diagnosis and appropriate treatment. A consensus meeting was held in London in May 2009. Those invited to attend included BAP members, representative clinicians with a strong interest in sleep disorders and recognized experts and advocates in the field, including a representative from mainland Europe and the USA. Presenters were asked to provide a review of the literature and identification of the standard of evidence in their area, with an emphasis on meta-analyses, systematic reviews and randomized controlled trials where available, plus updates on current clinical practice. Each presentation was followed by discussion, aimed to reach consensus where the evidence and/or clinical experience was considered adequate or otherwise to flag the area as a direction for future research. A draft of the proceedings was then circulated to all participants for comment. Key subsequent publications were added by the writer and speakers at draft stage. All comments were incorporated as far as possible in the final document, which represents the views of all participants although the authors take final responsibility for the document.

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To address the question of synchrony between two major biorhythms with a similar periodicity, the cortical rapid eye movement (REM)/non-REM sleep cycle and the enteric migrating motor complex (MMC cycle), we recorded upper small bowel motor activity and sleep activity during nocturnal and diurnal sleep in six healthy subjects. Motility was measured continuously using a fine (2.2 mm OD) and relatively comfortable nasojejunal probe with two pressure-sensitive microtransducers positioned under fluoroscopic control on either side of the ligament of Treitz. Sleep stages were recorded while the subjects slept in a sleep laboratory. Each subject was studied twice; once during normal nocturnal sleep and then after acute reversal of sleep by advancing the time of going to bed by 4 h each night for three nights. The total duration of sleep was similar for diurnal and nocturnal sleep. There was a significantly higher number of REM episodes (P less than 0.001) and REM sleep stage shifts (P less than 0.02) during diurnal (reversed) sleep. During sleep (both diurnal and nocturnal) there was a significant reduction in the MMC cycle length (P less than 0.02, P less than 0.03) and the duration of phase II of the MMC (P less than 0.009, P less than 0.02). The distribution of MMCs among sleep stages and REM sleep was consistent with a random distribution. These data show that periodic activity in the gut is modulated by the presence or absence of sleep, but they also are consistent with the hypothesis that the two cycles are independent and that one is not contingent upon the other.

The acute hypnotic effects of hydroxyzine 25 mg and 50 mg nocte, were examined in six male and six female volunteers. Continuous electrophysiological measures (C-EEG) were taken to assess both nocturnal sleep and sleep tendency the following day. Both doses produced significant reductions in sleep onset latency and decreases in waking during sleep; reciprocal increases in sleep duration were also seen. Female subjects demonstrated a greater hypnotic response, including a dose-dependent decrease in sleep onset latency. Increases in sleep duration following both doses were significant for the female group alone. C-EEG measures of increased drowsiness the following day failed to achieve significance; although the largest effects on daytime sleepiness, including dose-dependent increases, were again seen with the female subject group and corresponded with subjective ratings. These results demonstrate the hypnotic efficacy of hydroxyzine, whilst failing to detect significant C-EEG hangover effects. However, variability in response to antihistamines, registered here as differences between the sexes, requires further consideration.

The possible effects that sleep may have on long-term memory are first considered using the restorative hypothesis of sleep. This hypothesis proposes that protein synthesis is facilitated by sleep. The confounding role of circadian rhythms in previous sleep and memory experiments is also considered. Two experiments are reported. The first experiment investigated the effect of sleep on memory, in part using a sleep-deprivation technique. The second experiment controlled both for the interference effects and for possible non-specific effects of sleep deprivation. Results supported the restorative hypothesis and suggested that sleep was affecting memory by modulating trace consolidation.