If a pregnant woman is “eating for two” when she sits down for a meal, it’s also true that when she lies down at night, she is “sleeping for two”. The health benefits of sleep are particularly important for pregnant women and their children. Pregnant women often experience insomnia; sleep disturbances are among the most common side effects of pregnancy.
The very architecture of the sleep cycle can change in pregnancy. In the third trimester such disorders as sleep-disordered breathing and restless leg syndrome often appear. The first trimester more frequently sees the worst insomnia though; this is probably due to the initial changes in the serum hormone profile. (Indeed, there are differences in sleep architecture between younger women and post-menopausal women, even aside from pregnancy). Pregnant women have high levels of gonadotropin and progesterone; these hormones are soporific and thermogenic – they induce daytime sleepiness and early sleep onset. Pregnant women experience changes in melatonin, cortisol, thyroid stimulating hormone (TSH), and prolactin levels. Increased risks of insomnia coincide with the late luteal phase of the menstrual cycle, during and after pregnancy, and during the peri-/postmenopausal period.
Three trimesters were sometimes designated in folklore: weary, cheery, and dreary. There is some truth to this with regard to the sleep cycle. Women in the first trimester are prone to sleepiness due to higher levels of progesterone and nighttime urination which interrupts sleep. (Progesterone causes daytime sleepiness and nighttime sleep fragmentation.) Many women also experience nausea and vomiting during this period. Surveys show about a quarter of women experience first trimester sleep disturbance.
Pregnancy affects sleep through hormonal changes, physiologic changes, physical factors, and behavioral changes. Snoring and sleep apnea become more common as the woman gains weight.
Some doctors do allow their patients to take antihistamines during pregnancy, but as always when pregnant, women should consult their doctors before taking any medication, over-the-counter or otherwise.
The third trimester is the worst as far as sleep for the expectant mother. Three quarters of women report sleep disturbances in the final trimester due largely to the combination of hormone changes and the physical discomfort of an expanded belly. The sleep disorder Restless Leg Syndrome, which is fairly rare, strikes a third of women in the final trimester, although it almost always disappears after birth. The hormone estradiol is present in higher levels in women with RLS than those without. There is no acceptable treatment for RLS during pregnancy, although doctors usually monitor blood iron levels in such patients.
Nocturnal awakenings and shortness of breath also become more common in pregnancy. Some women also start snoring during pregnancy because the nasal passages swell. If the snoring escalates to apnea, the doctor should be immediately informed, as apnea cuts off air supply and can contribute to hormone surges. Snoring and sleep-disordered breathing in pregnant women has been connected to an increase in preeclampsia. When women who are at risk for preeclampsia become pregnant, their doctors screen them for snoring and sleep apnea. Sometimes these women are asked to be tested in a sleep study. Snoring and asthma have been found to be co-morbid in pregnant women, so asthmatic women should be especially vigilant for apnea.
About a quarter of pregnant women get obstructive sleep apnea, scientifically called gestational sleep apnea. The apnea is due to temporary distribution of body tissue during pregnancy. This is frequently undiagnosed because the woman does not have apnea until the third trimester and it disappears after delivery. Also, if a woman complains about tiredness or excessive sleepiness (symptoms of apnea) others may attribute these symptoms to the pregnancy, overlooking the possibility of apnea.
Disturbed sleep during pregnancy has also been shown to correlate with longer labor and increased risk for cesarean delivery. This is particularly true for troubled sleep in the third trimester. Women who experience migraine headaches on a regular basis are more likely to have short sleep times when pregnant. This tendency increases when the woman is obese.
A review suggests that napping is particularly good for pregnant women, as it does not have a significant effect on nighttime sleep.
Postpartum depression often results in insomnia, and sometimes insomnia contributes to postpartum depression. If the latter is the case, it is important that the insomnia be treated.