Experimentally investigated sleep disturbance of intensive care unit sounds

Patients at intensive care often report fragmented sleep from noise due to care activities from personal, from other patients and alarms. The aim of this study was to explore the effects of original and modified intensive care noises on sleep in 15 healthy subjects. Their sleep was registered with polysomnography during four nights, one adaptation night, one control night and two exposed nights with similar equivalent sound levels of 47 dB LpAeq, but with either a maximum sound pressure level of 64dB LpAFmax or 56 dB LpAFmax. The subjects also answered questionnaires and saliva cortisol was sampled in the morning. The results showed that during exposure nights, subjects had less slow wave sleep and spend more time awake. No relation was found between arousals and maximum sound levels. Apart from an unexpected reduction of time in the REM-stage for the exposure with lower maximum level, there was no impact of the reduction of maximal levels for the sleep parameters recorded. The subjective data supported the polysomnographical findings while cortisol levels were not affected by the conditions. For healthy subjects the reduction of maximal levels from 64dBA to 56 dBA was not enough to improve sleep quality