Disturbed sleep is a common problem — and one that has many serious consequences beyond feeling tired the next day. Research has linked insomnia and poor sleep to early mortality and diseases including diabetes and cardiovascular disease.
Women often report experiencing disturbed sleep more frequently than men. They also constitute the majority of patients in sleep clinics. Yet strangely, some studies show worse objective sleep quality in men – a bit of a paradox.
To understand what might explain the paradox, my colleagues and I conducted a study that directly compared sleep quality ratings and objective sleep measures between men and women.
We found that women complained more of sleep problems – but slept objectively much better than men. We think this paradox can probably be explained by men overestimating their sleep quality as they’re less able to perceive how often they wake up at night.
A total of 238 randomly selected women participated in the study, plus 238 men who were matched on age and BMI with the women to ensure similar participants were compared against each other.
Sleep was recorded in each participant’s home using a recorder that measured brain waves (electroencephalography – EEG), muscle tension (electromyography – EMG) and eye movements (electrooculography – EOG). These devices tracked what stage of sleep a participant was in and for how long, how much time they spent awake and how quickly they fell asleep.
A researcher visited the participant’s home in the evening, mounted the recording equipment and left. The participant went to bed and awoke at their usual time.
In the morning, the participant rated the degree of difficulty they had falling asleep, if their sleep was restless, if they woke up early, how often they thought they’d woken up, how long it took them to fall asleep, how long they slept and their overall sleep quality.
The sleep recording was scored by a sleep technician based on visual inspection of the EEG, EOG and EMG recordings. The data was then analysed to understand the objective quality of each participant’s sleep and its relation to gender and age.
Analyses were also adjusted for factors such as gender, age and alcohol consumption and smoking, which may affect sleep.
Sleep quality
The results show that women subjectively reported significantly lower sleep quality than men. Yet women actually had considerably fewer nighttime awakenings, less stage one (superficial) sleep and higher sleep efficiency (they spent more time asleep while in bed). Women also experienced more stage three (deep) sleep and slept longer (400 minutes versus 382 minutes for men).
Prostock-studio/ Shutterstock
The results suggest that women objectively had a good nights’ sleep, compared to men. The only variable that suggests worse sleep in women was that when they did wake up at night, they spent more time awake than men did – around nine minutes each time for women versus just under seven minutes for men.
It only takes around five minutes of being awake at night for a person to remember it the next morning. This may explain why women were better able to remember if they’d woken up the night before and estimate how many times they had. Men, on the other hand, grossly underestimated their number of awakenings (by 72% compared to women’s 37%).
For other quantitative measures, like time to fall asleep, sleep duration and time awake, men and women were equally good at estimating their objective values. And they were relatively correct.
We took this further and found that men who only woke up for a short period of time during the night (around eight minutes or so each time they woke up) often didn’t remember they had.
When this group of men was removed, no gender difference in subjective sleep quality remained. This suggests that men with short nighttime awakenings report better sleep quality than would be expected from their objective sleep measures as they didn’t remember they’d woken up.
It’s also noteworthy that men’s objective sleep deteriorated faster with age than women. This was particularly obvious for stage three sleep. While women aged over 65 got around 80 minutes of stage three sleep each night, men had only 53 minutes. Among those between 30 and 50 years of age, the amount was similar for men and women (around 70 minutes).
Sleep and wellbeing
A key reason women may complain of having a worse nights’ sleep than they objectively had may therefore be the amount of time they spent awake when they woke up, making it easier for them to notice. Likewise, men may overestimate their sleep quality because they’ve spent less time awake when they’ve woken up, so they don’t remember it happening.
Both findings would work towards reducing subjective sleep quality in women and increasing it in men. We assume then, that the experience of awakenings has an important influence on subjective sleep quality.
As our study was only conducted over one night, it will be important for future research to investigate whether these findings remain when participants are studied over longer periods of time.
Future studies may also want to explore the reasons for poor sleep in men – especially since common sources of disturbed sleep, such as alcohol, smoking and BMI, were all adjusted for in our analysis. Researchers may also want to investigate why men’s sleep becomes objectively worse as they get older.
Our research illustrates how sleep quality doesn’t just involve the physiological aspects of sleep. It also includes our own subjective experiences, which can impact our wellbeing and how rested we feel.
It also suggests that because many men overestimate their sleep quality, they may also overlook any sleep problems they’re experiencing. This could mean that some men aren’t getting help for conditions that could be affecting their health and wellbeing.
