STOCKHOLM — Researchers at Karolinska Institutet published a study in the journal Sleep Advances explaining why women often report poorer sleep quality than men, despite objective measurements indicating otherwise. The study suggests that men may not perceive or remember brief nighttime awakenings as readily as women do.

The study included 238 women and 238 men, ranging in age from 29 to 85. Participants recorded their sleep at home over one night using polysomnography, which measures brain activity, breathing, and movements during sleep. The morning after the recording, participants rated their sleep quality.

Objective measurements showed that women had fewer awakenings per hour than men. Women also exhibited longer total sleep time, higher sleep efficiency, and more deep sleep. Despite these objective findings, women were more likely to report poor sleep quality. Torbjörn Åkerstedt, Professor Emeritus at the Department of Clinical Neuroscience at Karolinska Institutet, said. "It's a paradox, but we have found a possible explanation for why sleep quality is perceived so differently by men and women."

The study found that women more accurately estimated the number of nighttime awakenings compared to men, who tended to underestimate their awakenings. Men, on average, spent less time awake per awakening than women. Men with short awakenings generally rated their sleep quality as good, while women typically rated their sleep quality as poorer regardless of the duration of awakenings. When men with short awakenings were excluded from the analysis, the difference in self-reported sleep quality between the sexes was eliminated.

Åkerstedt noted, "Our results suggest that men's more positive view of their sleep may be partly due to them not perceiving or remembering short awakenings during the night as well as women do." He added, "However, we don't yet know why that is." Sleep differences between men and women become more pronounced with age; at older ages, men experienced less deep sleep and more awakenings per hour, while women's objective sleep deteriorated to a lesser extent. Researchers also noted that measuring sleep over a single night may not reflect long-term sleep patterns.

The study was conducted in collaboration with researchers at Stockholm University and Uppsala University and was funded by the Riksbankens Jubileumsfond, the Swedish Research Council for Health, Working Life and Welfare, and the Swedish Heart-Lung Foundation. The researchers reported no conflicts of interest.