Women are more likely than men to report poor sleep, even though objective measurements show that their sleep is better in several respects, according to new research from Karolinska Institutet in Sweden.

“It’s a paradox, but we have found a possible explanation for why sleep quality is perceived so differently by men and women,” says Torbjörn Åkerstedt, professor emeritus at the Department of Clinical Neuroscience, Karolinska Institutet.

The researchers investigated differences in sleep between men and women, in terms of both objective measures and perceived sleep quality. 238 women and 238 men in Sweden, aged 29–85, recorded their sleep at home over one night using polysomnography, a method that measures brain activity, breathing and movements during sleep. The following morning, the participants rated their sleep quality.

The results, published in the journal Sleep Advances, reveal a clear pattern. On average, women rated their sleep quality as poorer than men, even though the objective measurements showed that they slept better. Among other things, the women had fewer awakenings per hour, a longer total sleep time, a higher sleep efficiency, and more deep sleep than the men.

Gender differences in memory

Women estimated the number of times they woke up during the night much more accurately than men, who underestimated how often they had been awake. On average, men spent less time awake each time they woke up. Men with short awakenings generally rated their sleep quality as good, whereas women generally rated their sleep quality as poorer, regardless of the duration of their awakenings.

When the researchers excluded men with short, barely noticeable awakenings from the analyses, the difference in self-reported sleep quality between the sexes disappeared.

“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,” explains Torbjörn Åkerstedt. “However, we don’t yet know why that is.”

The differences increased with age

The study also shows that differences in sleep 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. At the same time, women continued to report poorer sleep quality than men.

One limitation of the study is that sleep was measured over a single night and does not necessarily reflect long-term sleep patterns.

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