Anyone who has been sick can appreciate the joy of a good night's sleep, but in a large institution like a hospital, there are necessities of running the establishment that can disturb a patient's peace. All the more so with all manner of electronic equipment, cell phones, alarms, intercoms and such like, that produce sounds to wake the dead. However the association between noise disruption and sleep patterns had not been studied in great detail.
A report published in Annals of Internal Medicine goes some way to solving the issues with Orfeu Buxton, a neuroscientist at Brigham and Women's Hospital and Harvard Medical School in Boston, and his team looking into the problem in depth. As Buxton aptly puts it "It's nerve-wracking enough to be a hospitalized patient, and there's a lot of racket at night."
Patients agree: with one of their main complaints in a recent hospital survey being night time noise pollution but obviously there are practical considerations involved and as Jeremy Ackerman from Emory University School of Medicine in Atlanta, a member of the international Healthcare Acoustics Research Team puts it :
"We don't necessarily just have to make (the hospital) quieter ... We need to be particularly careful to avoid designing into systems and into the architecture very disruptive sounds ... we have a general sense that loud sounds, interruptive sounds all create an environment that is likely to slow healing."
Research has shown that background noise in a hospital can spike up to 80dB about as loud as a chainsaw. Obviously that kind of racket would wake most people up, but to make changes a more detailed evaluation was needed. With this in mind, Buxton's team took 12 healthy subjects and played sounds while they slept. The recordings were mainly taken from hospitals and included things such as IV pump alarms, people talking, a plane flying overhead and a laundry cart rolling down the hall. Using Encephalographic studies of the patients, and by using established sleep criteria, the subjects were tested during rapid eye movement (REM) sleep and non-REM stages 2 and 3.
In all they found that alarms and voices were the worst offenders, which makes sense, since alarms are designed to attract attention and the importance of what is being said tends to attract a person's attention more than the hum of an AC unit or a door closing. The brain can filter out those kinds of sounds as unimportant.
The noises were played one by one, until they either reached 70dB about as loud as someone shouting, or until the person woke up. An IV alarm for example, woke up most test subjects as quiet as 40db, and talking even as quiet as a whisper woke half the participants, during deep sleep and three quarters of them during light sleep.
Ambient noises, such as a flushing toilet, traffic noise, and a plane or helicopter flying overhead were much less likely to cause disturbance. To some extent the modern city life has immunized most people to these kinds of background noises, unless they live in extremely rural environments.
Sounds during non-REM stage 3 sleep, the deeper sleep, were less likely to cause arousals than sounds in non-REM stage 2. However researchers found rather unexpectedly that the probability of arousal to sounds presented in REM sleep varied less by sound type than when presented in non-REM sleep .
Researchers also found a slight increase in heart rate when a test subject was disturbed and while all the patients in the study were healthy, sick and elderly patients, would generally be more disturbed by the noises than less so. Dr. Jeffrey Ellenbogen, chief of sleep medicine at Massachusetts General Hospital, who co-led the study, confirmed his satisfaction with the results commenting that [The result] "gives us confidence this is a genuine physiological response (to hospital noises) in a negative way."
There are many things that hospitals can do to minimize noise, starting with simply closing a patients door, switching off unneeded equipment and keeping phone calls and talking in corridors close to patients rooms, down to a minimum. There are also design changes for new and refurbished premises that can take into account the patients peace over the practical functionalities of the institution. Obviously a hospital's ultimate objective is to heal people, and having a peaceful, non stressful environment ought to play a part in that.
Written by Rupert Shepherd