An American study has looked more closely at the effects of typical hospital sounds on sleep. Different hospital sounds were played at sound levels varying from 40 dB to 70 dB and under different sleep phases. The probability of arousal varied with sound type, sound level and sleep phase.
Less surprising higher sound levels were more disturbing than lower sound levels, and electronic signals like alarms and telephone signals, all designed to raise our awareness, were most disruptive for all sleep phases, but also voices and conversations affected sleep negatively. The results were also compared with cardiac data that showed that each disruption also affected heart rhythm.
The participants were most affected during deep REM sleep where the pulse went up up to ten beats per minute, but similar changes in heart rhythm were also seen in the more shallow sleep phases. The study was performed on healthy volunteers but indicate that the sound environment where we treat those already affected by illness also affect their sleep, and that there is reason to focus more on improving the sound environments in healthcare environments.
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