Menstrual Cycle and Sleep: What Does Current Science Say?

The menstrual cycle is accompanied by predictable fluctuations in sex hormones that affect not only the reproductive system but also the central nervous system, thermoregulation, cardiovascular function, and autonomic regulation. Sleep is one of the physiological processes sensitive to these changes.

Current research shows that the relationship between the menstrual cycle and sleep is considerably more complex than the assumption that sleep inevitably worsens during a particular phase of the cycle. In some women, sleep disturbances do occur predominantly during the premenstrual period and menstruation, but in healthy women with regular cycles, objective sleep parameters often remain relatively stable. At the same time, new data obtained using wearable devices suggest a possible reverse relationship: insufficient sleep duration is associated with greater menstrual cycle variability.

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What Is the Menstrual Cycle?

The menstrual cycle begins on the first day of menstrual bleeding. Traditionally, it includes the follicular and luteal phases, with ovulation occurring between them. In most women, the cycle lasts 21–30 days, while menstrual bleeding lasts less than 7 days.

During the follicular phase, follicles develop and estrogen levels, predominantly estradiol, rise. The increase in estrogen toward the end of this phase stimulates the luteinizing hormone (LH) surge, after which ovulation occurs. During the luteal phase, the corpus luteum produces progesterone and estrogen. In the absence of pregnancy, concentrations of these hormones decline, leading to the beginning of a new menstrual cycle.

Why are these changes important for sleep? Estrogen and progesterone receptors are present in central nervous system structures involved in sleep–wake regulation, including the basal forebrain, dorsal raphe nucleus, and locus coeruleus. Ovarian steroids may also influence circadian rhythms through the suprachiasmatic nucleus — the body’s principal circadian rhythm regulator (suprachiasmatic nucleus, SCN).

Does Sleep Change During Different Phases of the Cycle?

The answer is not straightforward.

Studies show that subjective sleep disturbances are reported more frequently during the final days before menstruation — the late luteal phase — and during the first days of menstrual bleeding. However, not all studies identify this relationship, and some detect only minor changes.

Individual variability is particularly important. In a study of 213 women, three different patterns of sleep difficulty across the cycle were identified: 46% showed no association between sleep and cycle phase, 25% experienced increased sleep difficulties in the middle of the cycle, and 29% experienced them immediately before and during menstruation. Anxiety, depressive symptoms, headache, cramps, and breast tenderness were also associated with sleep difficulties.

Thus, there is no universal pattern of sleep changes across the menstrual cycle. The response may depend on hormonal fluctuations, age, severity of premenstrual symptoms, pain, and individual sensitivity to hormonal changes.

What Do Objective Sleep Studies Show?

Objective sleep assessment is performed using actigraphy, wearable devices, and polysomnography (polysomnography, PSG).

In studies of young healthy women without pronounced premenstrual symptoms, no substantial differences are usually identified between the follicular and luteal phases in major sleep parameters such as duration, sleep latency, and sleep efficiency.

However, polysomnographic studies indicate that certain changes may occur in sleep architecture.

During the luteal phase, the proportion of N2 sleep increases — an intermediate stage of non-rapid eye movement sleep characterized by further reduction in brain activity, decreased muscle tone, and the appearance of characteristic sleep spindles. At the same time, the duration of rapid eye movement sleep (REM sleep) tends to decrease.

Slow-wave sleep (SWS), which represents the deepest level of non-REM sleep, and electroencephalographic slow-wave activity (SWA) do not change substantially.

Thus, the subjective perception of poor sleep does not necessarily indicate a pronounced disturbance in its objective structure or duration.

What Are Sleep Spindles and Why Do They Change?

One of the most consistent objective changes is altered sleep spindle activity — short periodic bursts of electrical brain activity recorded on electroencephalography during sleep. They are particularly characteristic of stage N2 and are considered an important component of normal sleep architecture.

Studies show that during the luteal phase, sleep spindle activity increases: spindles become more frequent and longer than during the follicular phase.

It has been suggested that this effect may be related to progesterone and its metabolites acting on gamma-aminobutyric acid type A receptors (GABA-A receptors). Hormonal changes across the cycle may therefore be reflected less in total sleep duration than in specific features of its neurophysiological organization.

Why Might the Luteal Phase Affect Sleep?

One of the most likely mechanisms is the effect of progesterone on thermoregulation.

During the luteal phase, body temperature rises, while the amplitude of its nocturnal decline becomes smaller. Skin temperature also increases. These changes may create less favorable conditions for the normal initiation and maintenance of sleep.

Changes also occur in cardiovascular regulation. During the luteal phase, heart rate during sleep increases by approximately 4 beats per minute compared with the follicular phase.

Thus, even in the absence of a pronounced change in sleep duration, the physiological context in which sleep occurs changes, including body temperature, heart rhythm, and autonomic nervous system activity.

What Have Wearable Devices Shown?

Of particular interest is the 2026 study by Gonzalez et al., which was based on a substantially larger dataset.

The authors analyzed more than 1.2 million observation days, 42,759 menstrual cycles, and data from 2,596 women. Participants used wearable devices that recorded sleep duration and several physiological parameters, including resting heart rate (RHR), heart rate variability (HRV), respiratory rate, skin temperature, and blood oxygen saturation.

This scale of observation makes it possible to assess not only average changes but also individual patterns in sleep and physiological parameters across large numbers of menstrual cycles.

Can Insufficient Sleep Affect the Menstrual Cycle?

One of the most interesting findings from Gonzalez et al. was the association between sleep duration and menstrual cycle variability.

Women who slept approximately 6 hours had greater menstrual cycle variability than those who slept approximately 8 hours. The authors also found that cycle duration was less variable when sleep duration exceeded 7.3 hours.

In addition, greater variability in sleep duration was associated with greater variability in menstrual cycle length.

However, it is important to emphasize that these findings demonstrate an association rather than a proven causal relationship. It remains impossible to determine conclusively whether insufficient sleep leads to changes in reproductive hormonal regulation or whether changes in the menstrual cycle themselves contribute to sleep disturbances.

What Happens to Sleep Immediately Before Menstruation?

The wearable-device study made it possible to objectively assess changes in sleep duration during different periods of the cycle.

A reduction in sleep duration of 10% or more was relatively uncommon but occurred more often during the premenstrual week. The analysis included 16,441 cycles in 425 participants; such a reduction in sleep was observed in 503 cycles. The likelihood of reduced sleep duration was higher during the premenstrual week than during other periods of the cycle.

At the same time, individual responses varied substantially. In 176 participants, an increase in sleep duration was observed at least once during the premenstrual week. This emphasizes the individual nature of sleep changes across the menstrual cycle.

Can Reduced Sleep Affect Physiological Parameters?

Yes.

In the study by Gonzalez et al., a 10% reduction in sleep duration was accompanied by an approximately 1.2% increase in resting heart rate and an approximately 2.8% reduction in heart rate variability. Changes in respiratory rate, skin temperature, and blood oxygen saturation were also observed.

However, the physiological response to reduced sleep did not differ substantially between menstrual cycle phases. In other words, insufficient sleep itself had a physiological effect regardless of which phase of the cycle it occurred in.

When Do Sleep Disturbances Become Clinically Significant?

Particular attention should be given to women with menstrual-associated disorders.

In premenstrual syndrome (PMS), emotional, behavioral, and physical symptoms occur predominantly during the late luteal phase and usually disappear shortly after the onset of menstruation.

Up to 18% of women may experience severe premenstrual symptoms that substantially affect daily functioning. Premenstrual dysphoric disorder (PMDD) occurs in approximately 3–8% of women. Sleep disturbances — insomnia or hypersomnia — are among the symptoms of PMDD.

Poor sleep quality is more common among women with PMS. In one study of female students, poor sleep quality according to the Pittsburgh Sleep Quality Index (PSQI) was reported in 80.5% of women with severe PMS/PMDD symptoms versus 56.4% in the control group.

At the same time, objective measures of sleep duration, sleep latency, and sleep efficiency did not differ substantially. This again demonstrates that subjective sleep quality and objective sleep parameters may not correspond.

Another important factor is painful menstruation (dysmenorrhea). Severe menstrual pain can impair sleep, daytime functioning, and emotional well-being. Therefore, when evaluating sleep disturbance during the perimenstrual period, it is necessary to consider not only hormonal changes but also the presence of pain.

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What Should the Physician Consider?

Taken together, the findings of the two studies support viewing sleep and the menstrual cycle as interrelated physiological processes.

First, worsening sleep should not be considered an inevitable feature of a particular phase of the menstrual cycle. In a substantial proportion of healthy women, objective measures of sleep duration and continuity remain largely unchanged.

Second, subjective sleep complaints are particularly important during the late luteal phase and menstruation, especially in women with PMS/PMDD, painful menstruation, and irregular cycles.

Third, when assessing sleep disturbances, it is reasonable to consider menstrual cycle duration and regularity, cycle phase, presence of pain, and severity of premenstrual symptoms.

Finally, wearable-device data suggest that insufficient and unstable sleep duration may be potentially important factors associated with menstrual cycle variability. However, a causal relationship has not yet been established. Gonzalez et al. emphasize the need for further studies that simultaneously assess hormonal parameters.

Practical Significance for the Physician

Current research demonstrates a bidirectional relationship between the menstrual cycle and sleep.

Fluctuations in estrogen and progesterone may alter thermoregulation, heart rate, and specific features of sleep architecture, including sleep spindle activity during the luteal phase.

Conversely, insufficient and unstable sleep duration is associated with greater menstrual cycle variability. The large wearable-device study suggests that sleep duration and stability may be relevant to reproductive health.

For clinical practice, this means that a woman’s sleep complaints should be evaluated in the context of her menstrual cycle, reproductive age, hormonally associated symptoms, and the presence of pain. This approach makes it possible to consider sleep disturbances not as an isolated problem but as a possible component of a broader complex of menstrual-associated symptoms.

References

1. Alzueta E, Baker FC. The Menstrual Cycle and Sleep. Sleep Medicine Clinics. 2023;18(4):399–413. doi:10.1016/j.jsmc.2023.06.003.
2. Gonzalez A, O’Day JJ, Johnson SC, Kim J, Jasinski SR, Holmes KE, Delp SL, Hicks JL. The menstrual cycle through the lens of a wearable device: insights into physiology, sleep, and cycle variability. npj Digital Medicine. 2026. doi:10.1038/s41746-026-02799-9.