Do Women Really Need More Sleep?
Let's break down the TikTok hype and look at the data.
Coauthored by Taisiya Reed and Julie Markhus
TikTok is a-buzz about a landmark study that shows women need more sleep than men. When we tried to find the study, however, all we found were quotes. So we dug deeper. Here is the data.
Current landscape of sleep medicine
The American Academy of Sleep Medicine and Sleep Research Society and Sleep Research Society suggests optimal sleep for adults is 7 hours per night.
There is currently no difference in recommendations between men and women.
Importance of sleep
All human beings spend about one-third of their lifetime in sleep.
Sleep is heavily influenced by circadian rhythms and by hormonal and environmental factors
Anxiety and depressive disorders are twice as common in women as in men
Sleeping ≤6 h = lower scores on tests of general cognitive function (GCA).
Sleep deprivation and insomnia have been related to the pathophysiology of Alzheimer's disease and would influence the symptoms and progression of the disease.
Short-term sleep deprivation heightens the brain’s response to pleasurable food stimuli, particularly in females, who exhibit 1.5 times higher limbic region activity in response to sweet foods than males.
Short sleep duration is associated with irregular menstrual cycles, which may impact reproductive health.
Gender differences in sleep
women sleep 11 mins more than men and were 2% more likely to nap
this means that women are more tired
ALSO is this gap large enough; even an extra 30 minutes of sleep for mothers might not compensate for their greater likelihood of waking to provide care.
Gender gaps in leisure time favor men
→ Less leisure and sleep time for women can mean fewer opportunities for physical and mental recovery.
Women are almost twice as likely as men to have poor sleep quality.
Women are 1.4 times more predisposed to insomnia than men
Women may also need to go to sleep earlier:
Melatonin is secreted earlier in women than men.
Core body temperature, which is at its highest before sleep and its lowest a few hours before waking, reaches its peak earlier in women than in men.
Women's intrinsic circadian periods are shorter than men's by around six minutes.
Females exhibit a nocturnal peak in the melatonin rhythm that is 38%–41% higher than males
Higher melatonin levels in females could imply a stronger alignment with or regulation of these circadian processes
Dr Renske Lok from Stanford University, who led the review, says:
"While this difference may be small, it is significant. The misalignment between the central body clock and the sleep/wake cycle is approximately five times larger in women than in men. Imagine if someone's watch was consistently running six minutes faster or slower. Over the course of days, weeks, and months, this difference can lead to a noticeable misalignment between the internal clock and external cues, such as light and darkness.”
Misalignment with internal body rythms can result in difficulty falling asleep, reduced sleep quality, and shorter sleep duration, all of which can contribute to poor sleep health.
Women had a higher prevalence of all sleep disturbances than men and colleagues, or physiological changes.
Menstruation: cramps, headaches, and bloating … report higher levels of daytime sleepiness, tiredness, and fatigue.
Pregnancy: During pregnancy, women may develop restless legs syndrome, a condition that makes it harder to fall asleep. Pregnant people are also more likely to experience depression, sleep apnea, pain, and incontinence, which disrupt their sleep. These sleep issues can persist into the postpartum period , when their hormone levels drop at the same time they start taking care of a newborn with an irregular sleep cycle — often resulting in even more daytime sleepiness.
Menopause: During menopause, up to 85% of women experience hot flashes. When these occur at night, women wake up in a sweat, thereby disrupting their sleep. The risk of developing sleep apnea also increases during menopause. This sleep disorder causes pauses in breathing that can interfere with the quality of one’s sleep. As a result, women with sleep apnea may feel less refreshed upon waking up and experience tiredness and excessive sleepiness during the day.
Sleep disruption by kids: Physical and emotional care for young children at night was largely provided by women, with a lack of explicit negotiation between partners about who provides this care, even when women return to employment.
A meta-analysis combining data from 29 studies reported that women were at a 41% greater risk for having insomnia than men in adult populations.
The trend of female predisposition was consistent and progressive across age, with more significance in the elderly.
The study showed that all subtypes of insomnia symptoms including DIS, DMS and EMA were more common in women than men.
Studies have also shown that women are more likely to nap during the day, which suggests their longer total sleep time may be misleading since some of it takes place during the day. Naps add to a person’s total sleep time, but they can also make nighttime sleep less restful.
Multiple studies have found that women fall asleep faster than men. This may suggest they have a greater need for sleep, but it could also suggest they are simply more tired on average.
Studies show women also spend more time in deep sleep than men. However, that changes in menopause, when women take longer to fall asleep and spend less time in deep sleep than men.
Duration per se may be a less important indicator of insufficient sleep than daytime sleepiness and problems such as frequently having trouble falling or staying asleep.
Female students reported higher sleepiness (lower wakeability) than male students.
Female students reported a longer sleep duration on free days than male students (suggests sleep debt).
Intrinsic desire for longer sleep duration might contribute to a higher susceptibility of female students to weekday sleep loss. …. Their natural sleep needs are not met, leading to a sleep deficit over the week.
For students, these might include decreased cognitive function, which can affect learning and memory; increased mood disturbances; reduced physical health; and greater susceptibility to stress.
Daytime sleepiness was associated with thinner cortex 😭
Temporal cortical thinkning predicted by presence of EDS and fatigue was equivalent to more than 3.5 and 9 additional years of aging, respectively. EDS and fatigue were associated with cortical thickness reduction primarily in regions with increased age-susceptibility, which may indicate accelerated brain aging.
Menstrual cycle effects on sleep patterns
Estrogen and Progesterone: primary hormones that fluctuate throughout the menstrual cycle and have a notable impact on sleep patterns. https://www.obstetricgynecoljournal.com/apdf/cjog-aid1105.pdf
Follicular/ ovulation phase:
→ higher estrogen → suppress melatonin production → difficulties in initiating sleep + potential sleep disturbances.
→ higher estrogen → enhance REM sleep → rise in the percentage of time spent in REM sleep, increasing from approximately 25.2% (±4.0%) compared to the luteal phase (20.5 ±4.7%).
Prior to ovulation women say they feel “more awake” at this time.
Luteal phase:
→ higher progesterone → sleep-promoting effects → REM sleep is earlier
→ higher progesterone → increased sleep disruptions due to thermogenic effects.
women usually feel more “sleepy” and “tired” during this time
melatonin + cortisol may also be reduced = dysregulation of circadian rhythm
minor decrease in rapid eye movement (REM) sleep during the luteal phase
Women on hormonal contraceptives had 6% higher prevalence of sleep disturbances and 17% lower prevalence of not meeting sleep duration recommendations. Women who used hormonal,contraceptives after adjustment for age.
Future research needed:
The current sleep recommendations simply do not accommodate for women. We encourage studies in the following areas.
There is a lack of human studies that document the influence of female hormones on PSG-recorded sleep to properly understand gender differences in sleep and help women understand their bodies.
Most sleep studies are not controlled for the menstrual cycle.
A determination regarding the actual recommendations of hours of sleep for women, also depending on their cycle.
Is there a link between sleep deprivation in women + Alzheimer's (which women are more prone to)?
This is so interesting! My insomnia began when I was 11 and got my period. It only got worse from there and I've never been a napper. I think my ideal holiday would be a week of catching up on sleep...