Sensory exposure of neonates in single-room environments (SENSE): an observational study of light

To measure the internal and external light exposure of incubators and open cots in an Australian single-room configured neonatal unit and compare findings to current recommendations.

Light meters were placed in the internal and external environment of incubators and open cots within occupied single rooms in a tertiary-level neonatal unit between 15 September and 28 October 2015. Data were recorded in one-second increments over a minimum of 48 hours per room.

Internal median light in incubators and open cots predominantly fell below 50 lux, with low amplitude diurnal cycling. Incubator covers substantially reduced external light exposure, contributing to very low light conditions (<10 lux). Periodically, light inside incubators peaked six times greater than the maximum recommendation of 600 lux. Overall, internal incubator and open cot lighting in the neonatal unit met American Academy of Pediatrics and American College of Obstetricians and Gynecologists recommendations for 65.1% of the time during the day and 25.6% overnight. Australasian Health Infrastructure Alliance recommendations were met for 6.7% of the time during the day and 2.4% overnight.

Overall, light levels fell predominantly below 50 lux with peak periods of extreme light exposure. Low amplitude cyclic light was evident, but it remains unknown if this is sufficient to produce an effect on circadian entrainment, especially in preterm neonates. Current guidelines do not stipulate optimal cyclic light levels in neonatal units to promote circadian rhythms in the newborn population. Further research to determine well-defined lighting parameters for neonates of different gestations is paramount.