The purpose of this study was to examine whether snoring adversely affects sleep architecture and sleep efficiency, and thus may account for the frequent complaints of daytime tiredness and fatigue expressed by heavy snorers. We recruited eight self-confessed heavy snorers and six self-confessed nonsnorers. All subjects had full nocturnal polysomnography, including continuous monitoring of snoring, which was quantified by counting the number of snores per hour of sleep (snoring index), the number of snores per minute of snoring time (snoring frequency), maximal and mean nocturnal sound intensity (dBmax and dBmean, respectively). We found that even the self-confessed nonsnorers snored lightly, with significantly smaller frequency and index than the heavy snorers. Sleep architecture was similar in both groups. Distribution of snoring among the sleep stages differed for light and heavy snorers: light snorers snored uniformly throughout all sleep stages, whereas heavy snorers tended to snore more during slow-wave and REM sleep. Snoring frequency and snoring index were similar during all sleep stages in light snorers, but they were higher during slow-wave sleep in heavy snorers. Wakefulness time after sleep onset and sleep efficiency correlated significantly with the snoring index. We conclude that although snoring does not affect sleep architecture in general, it influences sleep efficiency and wakefulness time after sleep onset; this may have an adverse effect on daytime function of heavy snorers.