Abstracts

Sleep has been shown to influence multiple physiological processes i.e. control of blood pressure, glycemia and protein synthesis, and deprivation of sleep could theoretically lead to sickness. Patients who are admitted to a hospital suffer disturbance of sleep due to external, medical and psychological factors. Disturbed sleep leads to decreased sleep latency. We hypothesized that in-patients have decreased sleep latency as compared to out-patients and that sleep latency decreases with length of stay. Otherwise completely normal EEG recordings were reviewed prospectively for sleep onset, which we defined as at 30 seconds of stage two of sleep or briefer if stage two of sleep was seen more than once. Patients with known sleep disorders, deliberately sleep deprived recordings and recordings with focal or generalized abnormalities were excluded. We noted medications, length of stay and if recording had been done in AM or in PM. Comparisons were done using the Mann-Whitney test and Pearson[apos]s for correlation. Thirty out-patient and 24 in-patient EEGs were reviewed. Mean sleep latency for out-patients was 16 minutes and 54 seconds (SD 11 minutes and 17 seconds) and for in-patients 11 minutes and 27 seconds (SD 8 minutes and 35 seconds). (P=0.0314). Length of hospital stay and sleep latency did not correlate. There was no statistical difference in age, number of patients on sleep enhancing medications or time of day of EEG between the two groups. In-patients have decreased sleep latency as compared to out-patients. This could be related to disturbed sleep. To see if this is a risk factor for poor recovery needs further investigation.