Al-Quran explains the creation of night and day as a sign of Allah’s power, while circadian rhythm is a science that studies the life rhythm of night and day cycle. An explanation of night and day in the al-Quran contains many significant guidance for enhancing the quality of human physical and spiritual. Among the guidance of the Quran and the Sunnah that can enhance the quality of human physical and spiritual are prayer, Qiamulail, fasting, Qailulah, exercising and practicing mannerism before bedtime. These teachings have a direct impact with the concept of human biological clock or circadian rhythms. Circadian rhythms are the rhythm of daily life that shape a person’s sleep and wake cycles during the 24 hours per day. This cycle affect the function of the lungs, heart, kidneys, glandular system, blood circulation, cognitive function and muscle strength of a person. Thus, the alternation of night and day will affect the production of certain hormones to overhaul the system and the cell body. However, the concept of circadian rhythm existing are far from the spirit of the al-Quran and Sunnah. Thus, the main objective of this article is to clarify the relationship between the teachings of the al-Quran, Sunnah and the concept of circadian rhythms. This article is a concept paper that combines “naqli” and “aqli” between guidance in the Quran and the explanation of circadian rhythms. The findings of this article found that all the rituals prescribed by the Quran and Sunnah can improve the quality of human physiology and psychology based on the concept of circadian rhythms.