We previously reported that dietary heat-killed Lactobacillus brevis SBC8803 affects sleep rhythms in mice. The present study evaluated the effect of consumption of heat-killed SBC8803 on sleep architecture in humans. A non-randomised, placebo-controlled, double blind, and crossover pilot study was conducted using volunteers who scored at a slightly high level (i.e. ≥6) on the Athens Insomnia Scale (AIS). Male subjects (n=17; age 41-69 y) consumed placebo or SBC8803 capsules (25 mg/day of heat-killed SBC8803) for 10 days. Electroencephalograms (EEG) were recorded using a mobile, one-channel system, providing objective data on sleep. Subjects’ sleep journals and administration of the AIS provided subjective data on sleep. Three subjects were excluded from the statistical analysis. Analysis of the remaining 14 volunteers revealed no significant differences between placebo and SBC8803 consumption in either the AIS or the sleep EEG. The sleep journals revealed an improvement in ‘waking’ for the SBC8803 consumption periods (P=0.047), and there was a marginally significant effect on ‘drowsiness during the following day’ (P=0.067). Effects on the EEG delta power value (μV²/min) were revealed by a stratified analysis based on age, AIS, and the Beck Depression Inventory (BDI). Specifically, effects were found among subjects in their 40s who consumed the SBC8803 capsules (P=0.049) and among subjects with a BDI score less than the all-subjects average (13.3) (P=0.045). A marginally significant effect was found among subjects with an AIS score less than the all-subjects average (11.6) (P=0.065). The delta power value of 5 subjects with both BDI and AIS scores less than the average increased significantly (P=0.017). While the number of subjects was limited, a beneficial effect on sleep due to consumption of heat-killed L. brevis SBC8803 was found in subjects with slightly challenged sleep.