The relationship between hormonal fluctuations and sleep remains complex. Estrogen can increase total sleep time and decrease sleep latency and arousal (3). Intravenous administration of progesterone has been found to produce a sedative effect. Low levels of estrogen and progesterone have been associated with increased susceptibility to insomnia (4). During the late-luteal phase when sex hormone levels are the lowest, the frequency of arousal from sleep increases. The number of awakenings is lowest during the early luteal phase when progesterone levels peak (5). An increase in sleep spindle frequency and a slight decrease in rapid eye movement (REM) sleep in the luteal phase have been observed. Regardless, there appears to be no significant changes in sleep patterns in relation to the normal menstrual cycle (5,6).

Sleep difficulties are often associated with menstrual-related disorders and symptoms. Premenstrual syndrome (PMS) is characterized by a set of physical and mood symptoms, including tenderness, irritability, and lethargy. PMS usually occurs during the late-luteal phase and ends shortly after the onset of menses. Premenstrual dysphoric disorder (PMDD) may occur if the symptoms are severe enough to disrupt daily functioning (3). Women with PMS or PMDD often complain about insomnia along with frequent awakenings and tiredness in the morning. Survey studies have confirmed the subjective inferences of sleep disturbances during the late-luteal phase. Polysomnography studies have been limited by small sample sizes and varying methodologies. There are no apparent reproducible differences between PMS/PMDD and sleep architecture (6). Selective serotonin reuptake inhibitors are suggested in treating premenstrual insomnia and PMDD (7,8). Hypnotics are commonly used to treat insomnia, and many patients usually use them for only a few days or weeks at a time (3). They may be effective in treating insomnia related to the menstrual cycle.

Restless legs syndrome (RLS) is a sensory-motor disorder characterized by uncomfortable sensations in the lower extremities and an urge to move them (9). The symptoms
usually worsen during the evening or night and can cause awakening from sleep. Diagnosis of the condition is based on patient history. RLS has been attributed to iron deficiency, and it has been found to increase in frequent blood donors. Women blood donors with RLS were more iron deficient than those without the condition (10). In a study that observed RLS severity across the female life cycle, 29% of the premenopausal subjects reported worsening symptoms of RLS during menstruation (11). The occurrence of RLS in menstruating women may be due to their higher risks of iron depletion due to blood loss through menses.

Sleep hygiene improvements or lifestyle modifications may alleviate restless legs. The patient should have a routine bed time and avoid sleep deprivation since this may worsen symptoms (12). Caffeine, alcohol, and nicotine can increase the prevalence of RLS. For occasional use, dopaminergics such as levodopa may be prescribed. For patients with persistent symptoms over a sustained time period, dopamine agonists may be effective. Opioids and anticonvulsants have also been suggested for the treatment of RLS. For menstruating women, oral iron supplementation may be enough to remedy the symptoms.

Insomnia during pregnancy can be caused by varying hormone levels, bodily changes, and psychological factors. During the first weeks of pregnancy, increased concentrations of estrogen, progesterone, prolactin, and human chorionic gonadotropin hormone can directly and indirectly affect sleep. Elevated levels of progesterone can cause sleepiness and fatigue (14). During the first trimester, total sleep time increases, although subjective sleep quality is worse. Backaches, nausea, and vomiting are common complaints during this time. Sleep is usually better during the second trimester as progesterone levels gradually increase, despite awakenings by fetal movements and heartburn. Decreased sleep time and increased arousals are associated with the third trimester. Women in the third trimester experience increased stage 1 sleep, increased awakenings, decreased sleep efficiency, and decreased REM sleep (5,14). Environmental noise cause frequent awakenings due to the decreased depth of sleep. Lower sleep quality is attributed to the growing fetus, leg cramps, anxiety about labor and delivery, and an increased urge to urinate from the enlarged uterus pressing on the bladder. Changing sleep behavior is an effective method for treating insomnia in pregnant women (4). Behavioral therapy includes relaxation techniques and sleep hygiene improvements. The woman is advised to avoid irregular sleep schedules, naps, and caffeine. Time spent awake in bed should also be minimized. Pharmacologic treatments should be approached with caution since most of these medications have not been studied in pregnant women.

Secondary RLS can develop because of iron deficiency, end-stage renal disease, and pregnancy. Nearly 20% or more of expecting mothers have reported RLS (13,15,16). The severity of the symptoms tends to worsen during the third trimester, although they are usually reversed after delivery (15,17). In a large epidemiologic study, most of the affected pregnant women were experiencing RLS for the first time (18). Compared with those without the symptom, those with RLS experienced less total sleep time, longer sleep latency, insomnia, and daytime sleepiness. The study also found that affected women had lower values of iron storage indicators than did healthy subjects. Another study showed that pregnant women with RLS had lower serum ferritin levels compared with those who did not have the symptom prior to conception and at each trimester (19). These findings suggest a metabolic link to the onset of RLS during pregnancy. The condition has also been attributed to a genetic predisposition. Studies have indicated that those with worsening symptoms of RLS during pregnancy had a family history of the condition (11,15,20).

Treatment of RLS in pregnant women has to take into consideration the safety of mother and child. Before considering drug therapy, sleep hygiene counseling should be considered. It is suggested that the same bed schedule be followed each day to better manage the circadian pattern of RLS (13). Expecting mothers are advised that caffeine, strenuous exercise, iron deficiency, and anxiety may make the RLS worse (15). When compared to pregnant women who did not take vitamins with folate, those who did had a lower prevalence of RLS (19,21). Taking supplements or eating folate-rich foods may decrease the incidence of the symptoms in expecting mothers. Medications containing dopamine antagonists such as ropinirole (Requip) or pramipexole (Mirapex) are the standard for treating RLS, but they may be unsafe for pregnant women (13). Dopamine antagonists can inhibit prolactin, which may interfere with lactogenesis. Benzodiazepines are generally not advised for pregnant women because of their potential risk to the fetus (15,22). Opioids have been suggested
as effective treatment for pregnant women (13). It is important to keep in mind that most of these drugs have not been extensively studied in pregnant women. Prior to a drug treatment plan, the risks should be discussed, and the lowest dose should always be used.

Pregnancy can lead to alterations in respiratory function and abnormal breathing. The effects of progesterone can lead to an increase in respiratory rate, and shortness of breath is common during the third trimester due to reduced functional residual capacity. Sleeping in the supine position could further compromise gas exchange (14). Snoring also increases during pregnancy and is reported in 14% of pregnant women, compared with only 4% of normal women (23). The symptom is most evident in women with obesity. In comparison to nonobese women at 12 and 30 weeks of gestation, women with obesity snored more and had lower levels of progesterone (24). The obese group had spent 50% of its sleep time snoring by 30 weeks of gestation. Snoring, obesity, excessive weight gain, and change in neck circumference during pregnancy are common predictors of obstructive sleep apnea (OSA) (1). Reports of awakenings due to choking have been found to significantly increase during the course of pregnancy (25). In one study, pregnant women with abnormal breathing patterns tended to be chronic snorers and exhibited abnormal blood pressures (26). Women with OSA have delivered babies with lower birth weights compared with those without the condition (27). Identification of the condition is important because it could lead to arterial hypertension, endothelial dysfunction, preeclampsia, and neonatal complications (1,14).