Like white noise, rhythmic motion is well-established as a calming technique for both infants
and adults. Slow rocking is effective at lulling us into sleep, as many have experienced when
swaying in a hammock, sleeping on a boat, or relaxing in a rocking chair. Researchers have
likewise found a positive association between motion and its soothing effect among infants – as
motion increases, fussiness decreases, and more time is spent in quiet sleep.(7) The sensory
stimulation that accompanies motion prompts a synchronizing action in the brain, which
supports internal sleep rhythms.(8)
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(4) Smith S. W., Ortmann A. J., & Clark W. W., (2018) “Noise in the neonatal intensive care unit: a new approach to
examining acoustic events” Noise Health, Aug 2018;20(95):121-130. doi: 10.4103/nah.NAH_53_17.
(5) Ibid.
(6) Parga J. J., Bhatt R. R., Kesavan K., et. al., (2017) “A prospective observational cohort study of exposure to womb-like sounds to stabilize breathing and cardiovascular patterns in preterm neonates”, Journal of Maternal-Fetal &
Neonatal Medicine, 31(17): 2245-2251, doi: 10.1080/14767058.2017.1339269
(7) Pederson, D.R. & Vrugt, D.T. (1973) “The influence of amplitude and frequency of vestibular stimulation on the
activity of two-month-old infants”, Child Dev,44(1):122-128.
(8) Bayer L, Constantinescu I, Perrig S, et al. (2011) “Rocking synchronizes brain waves during a short nap”, Curr Biol,
21(12):R461-R462. doi:10.1016/j.cub.2011.05.012
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Additional studies have described the beneficial effects of motion when compared to stillness.
Among a group of babies being held by their mothers, those carried by a walking mother (versus sitting) were calmer and exhibited less crying.(9) Apnea, or temporary cessations of breathing was significantly reduced among preterm infants placed in oscillating water beds versus regular beds.(10) The same type of bed was also associated with increased quiet sleep and a significant reduction of crying and fussiness.(11)
At its baseline level, SNOO is designed to slowly rock babies at a one-inch amplitude throughout
sleep, and in faster, shorter motions when the baby is crying. The SNOO’s motor is physically
limited in how far it can move. At the highest level, the amplitude is capped at approximately ¼
inch to either side, creating a jiggle that is similar to a mother holding her baby and bouncing on
a yoga ball or driving an infant in a car seat down a bumpy road.
The two fastest motions are often necessary for soothing very irritable babies (e.g., those
withdrawing from drugs). However, the factory default for SNOO is a setting called Motion
Limiter where the two highest levels of motion are blocked, unless the hospital staff chooses to
turn the setting off and enable all levels of bed movement (instructions available here).
SNOO has passed all requirements for certification by the ASTM, the Juvenile Products
Manufacturers Association, and the Consumer Products Safety Commission. However, we do
not recommend SNOO for infants with neurological or spinal defects, bleeding diathesis (e.g.,
hemophilia, anticoagulant therapy, intracranial bleeding), hydrocephalus, post-neurological
surgery, or any other condition that might contraindicate the use of a rocking bed.