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March 3, 2014

SickKids researchers advise parents about careful use of infant “sleep machines”

by Rebecca Milec

Crashing waves, chirping birds and the crackle of white noise are the sounds many parents play for their babies at bedtime to mask other noises that may keep infants awake. However, researchers are adding a cautionary note.

A new study led by The Hospital for Sick Children (SickKids) suggests that infant “sleep machines” (ISMs) are capable of producing hazardous sound levels that may be damaging to infant hearing and auditory development. The study is published in the March 3 online edition of Pediatrics.

The recommended safe exposure to noise for infants in hospital nurseries and neonatal intensive care units is a 50-decibel equivalent noise level over one hour. Researchers tested 14 infant sleep machines at their maximum operating volume at three distances: at 30 centimetres to simulate being in the crib or on the rail, 100 centimetres to simulate placement beside the crib, and across the room at 200 centimetres distance from the baby.  

The study showed that all of the 14 machines tested exceeded the recommended limits. Even when placed across the room at 200 cm, 93 per cent of the machines exceeded the limit. It is assumed that parents leave the machines on for much longer than the recommended one hour, usually for hours at a time while the baby is sleeping.

Frequent exposure to white noise could affect hearing, speech and language development, and could potentially cause possible hearing impairment. “We understand that life gets loud, but to me, it doesn’t make sense to drown out noise with other noise,” says Dr. Blake Papsin, principal investigator of the study and Otolaryngologist-in-Chief at SickKids. “We know that parents are trying to do what’s best for their babies and their sleep, so we hope this study informs the public about the potential harms, and educates them on appropriate use of the machine.”

“It is possible to use these machines safely, but without instructions or device limitations we cannot say that they are being used appropriately by parents.”

Papsin and his team provide recommendations to ensure safer use of infant sleep machines. They suggest that the machine is placed as far away from the infant as possible, at a low volume, and for a short duration of time. The researchers also say that music rather than pure white noise is better for infants because it varies in frequency and intensity over time.

The study recommends that policies are created for manufacturers. These include limiting the maximum output level, placing warning labels about noise-induced hearing loss, and requiring manufactures to include a mandatory timer with auto shut-off.

“An informed parent is the best parent. We are not saying not to use these machines. We are simply suggesting that they be used with caution, and other methods, such as lullabies and sound absorbers, be used whenever possible,” says Papsin.