Does a newborn know the difference between day and night?

As Hui Qun has mentioned, newborns are not able to tell the time difference yet. What I did was to establish a routine. In the mornings, I would pull open the drapes and let natural light fill in the house and by evening, I would close my drapes. By night time, the house would be quiet and dark, and I would put my baby to sleep after I have wipe him down and gave him his message. Gradually, it got easier as he recognizes the signs that it's sleep time.