Pregnancy is associated with a host of physical and emotional changes. Physical changes include morning sickness, body aches including back pain, heartburn and of course foetal movement. Emotional changes include a huge range including anxiety, fear and depression. Emotions can swing wildly. According to a National Sleep Foundation poll as well as other research, 78% of women experience more disruption of sleep than they normally experience. These changes vary with the stage of pregnancy:
In the first trimester there are high levels of progesterone. This may be associated with increased sleepiness. Some of the physical changes may also disrupt night time sleep, leading to further increases in daytime sleepiness.
The second trimester usually has less severe disruption of sleep than earlier or later stages, but still not normal quality sleep.
The third trimester is associated with the most significant changes in sleep. The physical changes of pregnancy are their greatest and include general discomfort, increased nocturnal urination, heartburn, back pain and nasal congestion. Studies have suggested that virtually all women have some disruption of their sleep in the third trimester.
In addition to the disruption of sleep that is a consequence of the physical and hormonal changes, certain specific sleep problems may also occur in pregnancy.
Because of the increased weight and the swelling of tissues that occurs in pregnancy, many women have the onset of snoring for the first time in pregnancy. If the airway obstruction is significant enough and in particular if there is a predisposition due to genetic factors, obstructive sleep apnoea may also occur. This condition is not only characterized by loud snoring but by obstruction of airflow which in turn leads to significant interruptions of sleep and drops in oxygen level. The interrupted sleep can lead to marked daytime sleepiness. If daytime sleepiness does occur and is more severe than might be reasonably expected from hormonal changes alone, the diagnosis of sleep apnoea should be considered.
In the third trimester as many as 15% of woman may also experience a sensation of discomfort, often described as a "creepy crawly" sensation in the legs which leads to a need to move, kick or even get out of bed and walk. This condition also occurs commonly in non-pregnant men and women but there seems to be an increase due to pregnancy. The consequence can range from being slightly annoying to severely disruptive of sleep.