My 4 month old son sleeps whole day and he is awake whole night. When they will come in normal routine like sleeping at night and playing in day time

A. it can take upto 6 monthds to be normal. baby s sleep is disturbed easily so make sure baby sleeps in a calm and comfrtable room. Good sleep is a must for brain and over all  growth of the baby. Baby should be well fed at bed time . Baby can wake up in between. You can use a music or can rock baby to sleep again. Baby can cry in between sleep so just make baby pat down to sleep again. .