I know, babies sleep a lot but how much is consider a lot? Some told me 20 hours in a day, some told me 18 hours. Out of curiousity, I went to google and found this :

1-4 Weeks Old : 15 ½ – 16 ½ hours per day

Newborns typically sleep about 15 to 18 hours a day, but only in short periods of two to four hours. Premature babies may sleep longer and colicky ones shorter.

Since newborns do not yet have an internal biological clock or circadian rhythm, their sleep patterns are not related to the daylight and nighttime cycles. In fact, they tend not to have much of a pattern at all — their needs are unpredictable at this age. And there is not much you can do about it. You have to go with the flow, do what works to soothe and comfort your baby, and be on “baby time.”

During transitions from wake to sleep and vice versa, you may see a sudden jerk or body twitch, as well as her eyes rolling upward as she falls asleep. As the brain develops, you may also see restless movements and agitation accompanied by crying for no apparent reason. This is all quite normal and no cause for alarm.

1-4 Months Old: 14 ½ – 15 ½ hours per day

5-8 Weeks Old

By 6 weeks old social smiling begins, your baby is beginning to settle down a bit, and you may notice more regular sleep patterns emerging. The longest periods of sleep run four to six hours and now tend to occur more regularly in the evening. Day-night confusion ends.

Two hours is about the longest time your baby can stay awake and remain happy and alert. So he needs to take a nap within that time frame. Waiting until your child is overtired or keeping him up past two hours often results in resistance to going to sleep, as well as fussiness and behavioral changes. Interestingly, if naps are deprived on a regular basis, his body produces stimulating hormones to fight fatigue that may actually cause night awakenings. So it is important to become sensitive to your baby’s sleep needs.

Learn to recognize early when your baby is becoming tired. Look for signs like rubbing eyes, pulling ears, getting circles under the eyes. Begin the wind-down routine right away; soothe him in a consistent manner that works for you, and then put him to sleep in his crib. He is now developing sensitivity to his surroundings, recognizing cues like light, noise, and vibration. So when sleeping, he should be motionless and in a quiet, darkened area. All this helps your baby become a more regular sleeper.

Resource : WebMD