What is the ruling on one who stays up at night and sleeps during the day?

Question:
The one who shifts his sleep to the daytime is said to be going against the Sunnah or the fitrah (the innate natural disposition). Is this correct?

Answer:
There is no doubt that it is contrary to what is prescribed. What is prescribed is that when one prays 'Isha' (the night prayer), he should sleep. The Messenger of Allah (peace and blessings be upon him) disliked sleeping before it and talking after it.
Many people nowadays stay up at night and sleep during the day. This is contrary to what is prescribed and contrary to the Sunnah.