Illuminance of neonatal units.

We have measured the illuminance (brightness) of seven neonatal units during both the day and the night. When the units were lit solely by fluorescent tubes the mean illuminance was 348 lux (range 192-690). During the day the mean illuminance was 470 lux (range 236-905). The high dependency regions in four of the seven units were significantly brighter than the corresponding low dependency nurseries at all times. In two of these units there is a policy of reducing the amount of artificial light in the low dependency areas at night, and in these the normal mean illuminance was 50 lux. We have measured the general levels of illumination to which a neonate might be exposed; the ocular exposure to light of a neonate depends, however, on both physical and biological factors and more research is required before an accurate estimate can be made.