Sleep enhanced and irritability reduced in preterm infants: differential efficacy of three types of waterbeds.

The purpose of this study was to determine whether waterbeds enhance preterm infants' sleep and reduce irritability, and whether plain, continuously, or intermittently oscillating waterbeds are differentially effective in producing these effects. The baseline states and motility of 52 stable preterm infants were assessed on two consecutive days for 100 minutes each. The infants then were randomly assigned to four groups: a control group who remained on the incubator mattress, or to one of the three experimental groups, each using a different waterbed. On days 3 and 4 in the assigned test condition, the infants' states and motility were again assessed for 100 minutes each day. The results indicate that, compared with infants in the control group, infants assigned to any of the waterbed groups slept significantly more and better, had significantly fewer unsmooth movements, state changes, and transitional states, and were significantly less irritable. Differential treatment effects were found, with infants on continuously oscillating waterbeds showing the most marked reductions in irritability, restlessness, state changes, and unsmooth movements. Thus, to enhance restful sleep and to reduce irritability and/or restlessness, it would be clinically advantageous to use waterbeds in the care of preterm infants. Since even the simple, nonoscillating waterbed improved sleep and reduced restlessness, the use of these beds would be the least costly to achieve these effects.