Sleep is not just an absence of wakefulness, but a well-defined collection of neurological events that plays an important role in your physical and psychological well-being, especially when you are pregnant. The sleep of older babies, children and adults can be divided into two different types. These are known as rapid eye movement (REM) and non-REM sleep. REM sleep is best known as the type of sleep in which you dream and is thought to play an important role in learning. Non-REM sleep can be divided into four stages. Stages 1 and 2 are called “light” and stages 3 and 4 “deep” sleep. During light sleep, you may still be aware of some aspects of your environment. However, during deep sleep, you are very difficult to rouse. Deep sleep is thought to play an important role in how rested you feel. If your sleep has been disturbed, you generally make up the lost REM and deep sleep, but not the light sleep. Between puberty and the menopause, you will probably sleep for about seven to nine hours in each 24-hour period and about one fifth of this time is REM sleep and four-fifths non-REM sleep.

The way you sleep depends on many factors related to your environment, family, genetic make-up, moods, general health and hormonal changes. In particular, women’s sleep patterns are influenced by the changes in the levels of different hormones during your menstrual cycle and when you are pregnant, breastfeeding or approaching the menopause. You may notice that you are really tired or sleepy or find it difficult to sleep during particular phases of your menstrual cycle, although this can be less apparent if you take oral contraceptives. These variations make it more difficult to set up, carry out and interpret studies on how women, rather than men, sleep. This means that some commonly accepted “facts” about sleep may not apply to women, especially when they are pregnant, have just given birth or are breastfeeding.

In practical terms, if you do not have any children and do not care for elderly or handicapped relatives, you can probably choose when and for how long to sleep. You may have to take account of the times at which you work and what is normal in your community, but most of the time you get to decide when you sleep. You may choose to go to bed and get up early, stay up late and sleep in or sleep less during the week and more at weekends. You are unlikely to have to attend to anyone else during the night. If you need to do anything at night, such as use the toilet or get a glass of water, you can do it and go back to bed quickly.

However, the way you sleep changes as soon as you become pregnant for the first time. It is even likely that once you have become a mother, you will never again sleep like you did before your first pregnancy. As soon as you become pregnant, you experience dramatic hormonal, physical and emotional changes. After the fertilized egg implants in your womb, the amount of pregnancy hormones that your body produces rise considerably. The size of your uterus and breasts increases and most of your organs have to work harder to support your unborn baby. You will probably feel more “emotional” and your mood may swing from high spirits to deep gloom and back again many times a day. If it is your first pregnancy, you will also start to become a mother in your own mind and in the eyes of the people around you. All of these changes can influence the way you sleep.

In the first three months of pregnancy, you will probably sleep more but have less deep sleep, feel sleepier during the day and have more difficulty sleeping at night than before you were pregnant. Your main sleeping position in early pregnancy may affect the place in your womb where your baby’s placenta implants. In turn, this may influence how you are most comfortable sleeping in the later months of your pregnancy. In the fourth to the sixth months of pregnancy, you will probably sleep about the same amount, but wake up more often during the night and still have less deep sleep than before you were pregnant. By this time, you may find that it becomes uncomfortable to sleep flat on your tummy, as this can put pressure on your womb.

In the last three months of your pregnancy, you will probably sleep less, wake up more often, have more difficulties sleeping at night and feel sleepier during the day than before you became pregnant. Your sleep may be disturbed by noises in or outside your home or because you have to use the toilet, your baby is moving, your tummy is uncomfortable, your legs are restless or you have heartburn or cramps in your legs. You will probably have more light, but less REM and deep sleep. These sleep problems can get worse as your due date approaches, particularly if you are expecting more than one baby. If you suffer from medical conditions, such as asthma, they may get worse and disturb your sleep more than usual. The times at which your baby is most active and when you wake up are probably related. This may help you get used to your baby’s activity cycle and prepare you for caring for and breastfeeding your baby.

Too little sleep is often associated with difficulties performing cognitive tasks. However, during your pregnancy, you can be confident that you can do the things that you normally do, but you may find new or complicated tasks more difficult than before you were pregnant.

It is important to discuss any severe sleep problems, such as heartburn, snoring, leg cramps or restless leg syndrome with your midwife or doctor. Sleeping medications are not normally prescribed during pregnancy because they may harm your unborn baby, but taking the vitamin or mineral supplements recommended by your health care provider may reduce sleep disturbances. There are also a range of things that you can do to help yourself feel less tired. Going to bed earlier in the evening or napping during the day or on the weekend may help you catch up on your sleep. Pillows designed to help support your whole body may help you feel more comfortable in bed. Drinking less during the evening and night may reduce the number of times you have to use the toilet at night and avoiding things like strong tea, coffee and cola, which contain a lot of caffeine, can improve your sleep. Finally, try to sleep when your baby is resting. This is good practice for after the birth, when your baby may need a considerable amount of care and attention at night!