Hi Arpita, babies this small do not sleep as they should. If he has trouble sleeping since beginning, you will need to set up a sleep schedule for him. I have written a post about it few days back, you can give it a read if you want..

<a href="http://app.babychakra.com/article/2661">Infant Sleep Training - Here&#8217;s What Worked For Me</a> 
<a href="http://app.babychakra.com/article/3257">Go To Sleep, My Baby</a>

My baby is 74days old. I m facing a sleep problem with him. He neither sleeps the whole day and at night too he sleeps less . Wants to sleep but can't so he keeps on crying. What to do?