Failure of an electric rocking device to improve neonatal sleep

We wanted to investigate whether an electric rocking device (Swing2Sleep, Neumünster, Germany), sold with the claim to promote infant sleep, would increase total sleep time or reduce sleep latency once infants are put therein.

In a randomised crossover design, 20 infants (median gestational age at birth 31.7 weeks, range 25-39) were placed to sleep either first with the device rocking, then not rocking (or vice versa) for 5-7 h each. The device consisted of a hammock with three spiral springs that performed vertical swings at a rate of 100/min and an amplitude of 2.5 cm.

There was no significant difference in %time spent asleep (83 (22-97) vs. 85% (49-96)), sleep latency (7.7 (2-45) vs. 12.3 (4-42) min), sleep fragmentation (1.3 (0.5-2.3) vs. 1.1 (0.2-5.5)) or efficiency (0.8 (0.2-1.0) vs. 0.9 (0.5-1.0)) between both conditions.

At its recommended settings, the device did not achieve its intended effect in these infants.