Live Harp Music Reduces Activity and Increases Weight Gain in Stable Premature Infants

Abstract

Dear Editor: Music enhances weight gain in premature infants on fixed feeding regimens.1 To better understand the mechanism of this effect, we assessed the effects of live harp music on salivary cortisol (SC), heart rate variability (HRV), and activity in a pilot study of 8 stable premature infants. All infants were at least 34 weeks gestation, had passed a newborn hearing screen, and had no medical conditions or medications affecting cortisol levels, cardiac function, activity, or caloric intake. Infants were randomly assigned to usual care (4), quiet room (2), or harp music (2) for 45 minutes at the same time daily for 3 days. For the quiet room, infants were moved to a room used for transition to home where noise levels were approximately 30 decibels quieter than in our intermediate care nursery. For the harp music group, the infants were moved to the same room, but provided with 45 minutes of harp music, with volumes similar to those in usual care. Outcomes were measured at the same time daily. SC was measured twice (before and after the intervention, approximately 1 hour apart). HRV was measured using a MiniMitter 2000 (MiniMitter Inc., Bend, OR) and calculated in standard fashion.2 Activity was measured using a wristwatch actimeter (Actiwatch Model 64, Respironics Inc., Pittsburgh, PA), placed on the left lower leg. This study was approved by the Institutional Review Board of the Wake Forest University School of Medicine. At baseline, the 8 study infants had an average gestational age of 36.4 weeks and weight of 2279 grams, which was similar for all three groups. Weight gain during the study was greatest in the harp music infants (average gain of 19.1 g/kg-day), next highest in the quiet room infants (17.2 g/kg-day), and least in the usual care infants (13.3 g/kg-day) (p < 0.05). SC and HRV parameters were similar in all three groups; SC fell equally in all groups. Activity fell by approximately one order of magnitude in the 2 hours after the study intervention (from 5000 to 490 movements per hour, p < 0.01). This activity change was not observed in the other groups. Music may enhance weight gain by decreasing activity and caloric expenditure. Although it is not possible to rule out effects of music on SC or HRV, these pilot data suggest that larger studies should focus primarily on the effects of music on activity to promote weight gain in premature infants.