A hat (200) for a neonate (120) comprising: a central portion (201), a first side portion (202) and second side portion (203) attached to opposite sides of the central portion (201), a first fastener (208)； a top flap (204) and a second fastener (211). The hat (200) has an unfolded configuration and a worn configuration. In the unfolded configuration the first and second portions (202, 203) extend away from each other from the central portion (201) in opposite directions. In the worn configuration the hat (200) wraps a neonate's head with the central portion (201) in contact with the back of the neonate's head, the first portion (202) wrapped around a first side of the neonate's head and the second portion (203) wrapped around a second side of the neonate's head. The first and second portions (202, 203) are configured to be fastened together in the worn configuration by the first fastener (208) so that the first portion (202), central portion (201) and second portion (203) together define a hat (214) rim encircling the neonate's head. The top flap (204) is configured to cover the top of the neonate's head in the worn configuration. The top flap (204) is configured to be fastened to at least one of the first, central and second portions (202, 201, 203) by the second fastener (211). The hat (200) further comprises an optical physiological sensor that comprises: a flexible circuit board, a light emitter (310) and a light detector (311)； the flexible circuit board having: a sensor portion (302) to which the light emitter (310) and light detector (311) are connected； a module portion (305) including contacts (304) for electrically connecting the light emitter (310) and light detector (311) to a removable readout module (400)； and an elongate lead portion (301) between the sensor portion (302) and module portion (305).Chapeau (200) pour un nouveau-né (120) comprenant : une partie centrale (201), une première partie latérale (202) et une seconde partie latérale (203) fixée
