Sleep patterns in intensive care unit patients: a study using the bispectral index.

OBJECTIVE To objectively record sleep patterns in intensive care unit patients using the Bispectral Index as an electroencephalographic measure of sleep and to determine if the sleep pattern is correlated with various clinical factors. METHODS Adult intensive care patients were recruited who were in the recovery phase of their illness and on minimal sedation. The sleep pattern was examined using an overnight recording of the patient's Bispectral Index and submental electromyogram. RESULTS Twenty-seven adult patients in a tertiary level general intensive care unit were enrolled. The sleep pattern was examined using an overnight recording of the patient's Bispectral Index and submental electromyogram. No intensive care unit patients showed a completely normal sleep pattern, but about half showed 40-90 min cyclical periods of slow wave sleep that approached a normal sleep pattern. CONCLUSIONS Traditional classifications of EEG sleep staging are deficient when used to describe sleep in intensive care unit patients.