What is the way to get rid of excessive sleep and constant lethargy, and what is the correct number of hours for sleep?

Strengthening faith, performing obligatory and supererogatory prayers, and remembering Allah, all strengthen resolve. Among the supplications of the Prophet was: "O Allah, I seek refuge in You from anxiety and sorrow, from incapacity and laziness, from stinginess and cowardice, from the burden of debt and from being overcome by men." Qiyam al-Layl (night prayer) increases vitality, for whoever remembers Allah, performs ablution, and prays, awakens with energy and a good soul. Moderate sleep is eight hours.