During pregnancy you should sleep however you feel comfortable but lying on your back after around 16 weeks can be uncomfortable.
Everyone moves around during their sleep so whilst it might be best for you to avoid falling asleep on your back, don't panic if you wake up in a different position.
Sleeping on your side might be a better option. You can support your bump with extra pillows, and put a pillow between your knees.
Towards the end of pregnancy, as your bump becomes bigger and heavier, you might find it more comfy to sleep propped up in an almost sitting position. Use cushions, pillows or an extra duvet to make sure you're comfortable. Some women find that sleeping like this can sometimes help with pregnancy heartburn too.
Try to relax before bedtime by taking a bath, reading or listening to some relaxing music. Having a sensible and healthy diet will help you too.
If you aren't sleeping well keeping active could help. You could join an antenatal yoga or pilates class, but make sure the instructor knows you are pregnant. Exercise can help you to feel less tired, so even if you're feeling tired during the day try to get some activity, such as a walk at lunchtime or going swimming. If the lack of sleep is bothering you, try talking to your partner, a friend, doctor or midwife.
For more information on pregnancy health and advice go to www.nhs.uk/Start4Life