New babies will initially sleep for approximately 18-20 hours a day when first born. As they get older this gradually decreases. You may find with a new baby born by caesarean to be very sleepy in the first few days, this is due to the drugs used in labour wearing off. It would be advisable to wake him for feeds every 3-4 hours if not waking naturally. Do not allow to go over this time especially if breast feeding. It is important to feed little and often in the first few days to stimulate the milk flow. If breast feeding your baby will only be getting colostrum which is a watery fluid. Although colostrum is very nutritious it is not very satisfying, so your baby will feed more frequently. He may only feed for 5 minutes at a time, then tire or doze off to sleep again, this is perfectly normal.
It is very tempting to let your baby sleep longer particuarly at night, however he or she will need to feed up to 12 times a day, less so with bottle feeding. Regular breast feeding will help stimulate the milk glands ready for when the mothers milk comes in around day five. If your baby is crying alot and not sleeping, see if he has wind by holding him over your shoulder or over your knee leaning slightly forward and gently rub his back. If he carries on crying offer more milk. If crying persists for long periods after feeding and winding ask a member of staff or health professional to check your baby is not in any other pain.
Baby sleep in the first few weeks is often quite random with no particular pattern, allow your infant to let you know when they are hungry. The most important thing is that you are enjoying your baby, if you are relaxed then your baby will be too and is likely to sleep for longer periods. When new babies are sleeping they often make funny little snuffly noises, this is because their airways are so small but at least you can be reassured they are breathing normally.
As your baby develops his sleep patterns will become more regular and you will notice him or her getting into a daily routine as he grows bigger each day. Don’t expect too much in the first few weeks though, you will find that just as you are getting used to one pattern a new one emerges!
By 8-12 weeks your baby should be feeding every 3-4 hours and having longer stretches at night. Some lucky mums have babies that sleep through for 6 hours or more. Of course every baby is different so don’t go comparing your baby to your friends’ just enjoy those precious first  few weeks.