Sleep duration is associated with auditory radiation microstructure.

OBJECTIVES Although hearing has been shown to interact with sleep, the underlying mechanisms for the interaction remain largely unclear. In the absence of knowledge about the neural pathways that are associated with hearing-sleep interaction, this study aimed to examine whether the auditory radiation, the final portion of the auditory pathway from the cochlea to the cerebral cortex, shows association with sleep duration. METHODS Using Diffusion Tensor Imaging (DTI) data from enhanced Nathan Kline Institute-Rockland Sample (NKI-RS), we isolated the white matter tracts between the medial geniculate nucleus of the thalamus and Heschl's gyrus in each individual subject (N = 465) using probabilistic tractography. As a measure of the white matter microstructure integrity, the mean fractional anisotropy (FA) of the whole auditory radiation was examined and tested for an association with sleep length in the Pittsburgh Sleep Assessment Index. RESULTS A significant inverse-U shaped association was found between the auditory radiation FA and sleep duration. DISCUSSION It is suggested that the auditory radiations are a part of the pathway mediating the sleep-hearing interaction. Although the current study does not resolve the causal relationship between hearing and sleep, it would be the first evidence that the auditory radiation is associated with sleep duration.