Infant Sleep Machines

Are ISMs safe for baby’s delicate hearing?

Infant Sleep Machines

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Popularized by sleep experts and parents alike, infant sleep machines (ISMs) have become “must-haves” on nursery wish lists.

These machines produce white noise, nature sounds, lullabies, heartbeats, and more. Manufacturers suggest that ISMs be placed near or on an infant’s crib to mask external sounds that may keep baby awake. For already sleep-deprived parents, ISMs may seem a win-win situation for all.  But are they?

A team of researchers at the University of Toronto and Sick Kids Hospital set out to determine just how loud these devices are and what impact they may have on baby’s hearing and auditory development. Here’s what they found.

Study raises concerns

The current recommendations from manufacturers about safe use of infant sleep machines are vague at best. Instructions tell parents to play machines continuously and at a level equal to or louder than an infant’s cry. But there is next to no mention of potential risks of white noise exposure.

The study, which appears in Pediatrics, measured the sound output from 14 infant sleep machines at distances of 30 cm, 100 cm, and 200 cm (to mimic placement of the machine on the crib rail, near the crib, and across the room). A sound level meter fitted with a coupler was used to simulate the inner ear canal of an infant – no babies were used in this study.

For adults in the workplace, the noise exposure limit is 85 decibels over an 8-hour period. Exposures above that can lead to hearing loss. For infants, 50 dB (the level of normal conversation) over one hour is the recommended maximum safe exposure limit in hospital nurseries and neonatal intensive care units.

Results of the ISM study show that at the ‘in the crib’ and ‘beside the crib’ distances, all 14 machines exceeded 50 dB over 1 hour. Three of those machines exceeded 85 decibels. At the ‘across the room’ distance, 13 of 14 machines exceeded 50 dB. “We suggest that the consistent use of these devices raises concerns for increasing an infant’s risk of noise-induced hearing loss,” say researchers.

Tips for parents

ISMs can produce sound intensities in excess of the current recommendations for infants, which may place them at risk of noise-induced hearing damage and auditory mal-development. Researchers say that, “The safe use of an ISM may be possible but requires policy recommendations for manufacturers, including limiting the maximum output levels.”

Meanwhile parents who use these devices should:
›place ISMs as far away from infants as possible (>200cm)
›limit the duration of ISM use so that exposure is not continuous.

Author: Dr. Kristi Prince, ND

Dr. Kristi Prince, ND is a Naturopathic Doctor in Cobourg with a focus on Family Medicine and Women's Health.  She is also a soon-to-be registered lactation consultant.

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