Get Some Sleep: Pregnant and tired

Lisa Shives, M.D., is the founder of Northshore Sleep Medicine in Evanston, Illinois. She blogs on Tuesdays on The Chart. Read more from her at Dr. Lisa Shives’ Sleep Better Blog.
Poor sleep is such a common complaint during pregnancy that probably many women and even their doctors think it's is a normal part of pregnancy.
While it is true that pregnancy has a significant impact on the quantity and quality of sleep, it is also true that many of the sleep problems that arise during pregnancy can be treated or ameliorated.

It is common for women to feel extreme sleepiness and fatigue in the first trimester, which is assumed to be secondary to rising progesterone levels because progesterone is known to have a hypnotic affect. Progesterone levels continue to rise throughout pregnancy yet in the second trimester most women report feeling more daytime alertness and they feel that their sleep quality is improved compared with the first trimester.
The third trimester ushers in a host of problems that are mostly connected to the increased girth. During the later months, women often experience shortness of breath and reflux because  their diaphragm is elevated, pressing on the lungs and the stomach. They also have to urinate frequently during the night. That alone is quite a disruption to sleep.
These are normal problems encountered during pregnancy and there is not a lot a doctor can do about it. However, there are other sleep problems that represent the emergence of a bona fide sleep disorder and these can be treated.