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Influence of light type exposure at nighttime on resting time and 6-sulfatoxymelatonin level of postpartum women in the rooming-in unit


The Postpartum woman's sleep and wake cycle changes to attend the demands of the newborn. Thus, constant exposure to artificial light can compromise total sleep time and synthesis of 6-sulfatoxymelatonin, a hormone that synchronizes biological rhythmicity.


To evaluate the influence of artificial light types at night on rest time and the 6-sulfatoxymelatonin level of hospitalized postpartum women.


Clinical trial performed with puerperal women admitted to a University Hospital in São Paulo-Brazil. Postpartum women aged of 18 years or over, whose child was born at term, healthy and breastfeeding, had a postpartum period greater than or equal to 12 hours, single pregnancy, no history of psychiatric, thyroid and/or sleep disorders, who did not use illicit drugs during pregnancy, and have not worked at night for the past three years were included. Blind women, taking beta-blockers, diuretics, corticosteroids and/or central nervous system depressant medication were excluded. Eligible postpartum women were allocated randomly in the rooms with different light. The control group was characterized by mothers who were exposed to white light (Osram®), commonly used by the service. In the experimental group, the puerperal women were assigned to the room with long wavelength emission light (Align PM®). Data were obtained between 2018 and 2019 after approval of ethical merit. The total resting time and 6-sulfatoxymelatonin level were measured during 24 hours, respectively, by ActTrust® actimeter and ELISA method. Fisher, Shapiro-Wilks, Levene, Mann-Whitney and t-tests were used, with significance level of 5% and power of 80%.


Twenty-one postpartum women, 11 in the control group and 10 in the experimental group were analyzed. The average night rest time was similar (p = 0.89) between the experimental (6.8 hours) and control (6.9 hours) groups. The mean diurnal and nocturnal percentage of the total 6-sulfatoxymelatonin load excreted was similar in the control groups (47.4 and 52.5 µg/period) and experimental (47.6 and 52.4 µg/period), respectively (p>0.05).


The type of artificial lighting did not affect the rest time and 6-sulfatoxymelatonin level of hospitalized postpartum women.


Circadian Rhythm; Melatonin; Lighting; Postpartum Period, Nursing


Área Clínica


Eliana Moreira Pinheiro, Cristina Furtado Volcov, Fernanda Gaspar do Amaral, Miriam Harumi Tsunemi, Ariane Ferreira Machado Avelar, Bruno da Silva Brandão Gonçalves, Kelly Pereira Coca