Ahsan Allahu Ilaykum Sheikh, not praying is only excused by sleep or forgetfulness. Now I´ve been wondering what if someone is sick and he got medicine from the doctor. Yet he sleeps for 12-15 hours daily because of the sickness. Does he repeat his Salah or is he excused due to continues sickness ?

Ustadh AbdulAziz al-Haqqan

They must pray, so they sleep and pray, and then they go back to bed. If they were not able to wake up because of the heavy medication, then there is no problem: once they wake up, they can make up the salah that they missed.