Pregnancy: Sleeping for Two
Pregnancy is an exciting and physically demanding time.
Physical symptoms can interfere with sleep (body aches, nausea, leg cramps, fetus movements and heart-burn), as well as emotional changes (depression, anxiety, worry).
Thus, in the NSF poll, 78% of women reported more disturbed sleep during pregnancy than at other times although some women have few sleep problems. 
Sleep associated problems also become more prevalent as the pregnancy progresses.
One current study reported that changes in sleep occur in 13-20% of women in the first trimester and increase to 66-90% by the third trimester.
Generally, nausea can be experienced early whereas general discomfort may disrupt sleep later in the pregnancy.
First Trimester (Months 1-3)
In general, women have lower quality of sleep during the last trimester of pregnancy.
- High levels of progesterone are produced, increasing feelings of sleepiness. Also, an enlarged uterus can press up against the diaphragm, making it more difficult to breathe.
A woman wakes up during the night to urinate increases as well. Troubled sleep patterns may begin.
Deprivation of sleep can cause daytime sleepiness. Women are inclined to sleep more during this time than before they were pregnant, or later in pregnancy.
Second Trimester (Months 4-6)
During this trimester, the growing fetus reduces pressure on the bladder by moving above it and decreasing the need for frequent bathroom visits.
Sleep excellence is still worse than it was before pregnancy and many women become restless as they search for a comfortable position.
Third Trimester (Months 7-9)
Women experience the most pregnancy-related sleep problems at this time although they may sleep longer and nap more by the end of the pregnancy. Women may often feel physically uncomfortable.
Leg cramps, heartburn and sinus congestion are common reasons for disturbed sleep, as is an increased need to go to the bathroom. (The fetus puts pressure on the bladder again.) One new study reported that by the end of pregnancy, 97% of women were waking during the night.
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