Hadith.1442 - Al-Baqir عليه السلام said:
"Sleeping at the beginning of the day is wastefulness, the nap at midday is a blessing, sleeping after Asr (afternoon prayer) is foolishness, and sleeping between the two night prayers (Maghrib and Isha) deprives one of sustenance."
There are four types of sleep : the sleep of prophets is on their backs due to their communication with revelation, the sleep of believers is on their right sides, the sleep of disbelievers is on their left sides, and the sleep of devils is on their faces.
