Volcov, Cristina FurtadoPinheiro, Eliana MoreiraTsunemi, Miriam Harumi [UNESP]Amaral, Fernanda Gaspar doAvelar, Ariane Ferreira MachadoHocking, JenniferCoca, Kelly Pereira2022-05-012022-05-012021-01-01Revista brasileira de enfermagem, v. 74, n. 6, p. e20201064-, 2021.1984-0446http://hdl.handle.net/11449/233525OBJECTIVES: to compare the parameters of the activity/rest cycle of early postpartum breastfeeding women under a controlled and uncontrolled long wavelength ray light regimen. METHODS: quasi-experimental study with breastfeeding women and their babies during postnatal rooming-in, São Paulo, Brazil. Participants were allocated to either an experimental (intervention) or a comparison group. The intervention involved exposure of the woman in a controlled room with artificial long wavelength ray light at night. Each woman's level of 6-sulfatoxymelatonin at 24 hours and activity/rest times was analyzed. RESULTS: the mean activity/rest times of women in the experimental and comparison groups were similar. The mean percentages of total load of 6-sulfatoxymelatonin during the day and night were similar (p=0.09). At 24 hours, the experimental group presented a significantly lower mean percentage of total load compared to the comparison group (p=0.04). CONCLUSIONS: women who stayed in the room with long-wavelength artificial light showed no difference in activity/rest and 6-sulfatoxymelatonin levels in the early postpartum period.e20201064engArtigo10.1590/0034-7167-2020-10642-s2.0-85114753491