During his first weeks of life, light plays an important role in synchronising the biological clock and then the asleep/awake rhythm of the baby.
And it's right the light/darkness alternation that helps the stabilization of this rhythm: we can then prepare a light environment for the moments of wakefulness, while a softer light will be associated to sleeping.
In particular, we can keep the room dark and basically quiet during the night sleeping, when the whole family is resting; for his daytime nap, the baby can sleep in the twilight and in a room which is not completely removed from the household noises which have a reassuring effect on the baby.
After he reached his six months of age, the baby may experience a period of unquiet sleeping, caused by the so called separation anxiety, which may cause night awakenings, nightmares or fear of darkness.
In this case, a soft, low intensity light, positioned so that it can not be directly gazed upon by the child, can reassure him if he awakens.
From a practical point of view, moreover, a night light placed in the room allows the parent to rush to the child of any age, orienting with ease without the need to have excessive light in the room.