How can I expect my sleep to change in pregnancy?

Depends. Some people have no problems while others have significant sleep disturbances. Try staying active and doing yoga before bed.
Pregnancy and sleep. With weight gain you may snore more and, depending on the degree of snoring/breathing difficulties during sleep, this may cause more fatigue and tiredness during the day. Restless legs syndrome can also occur specifically during pregnancy. Insomnia can also occur, particularly due to discomfort. Some medications can be used to help sleep but best to avoid them if possible, esp near delivery.