Reference: Fataawa Ramadhaan – Volume 2, Page 522, Fatwa No.487
Fataawa Ibn ‘Uthaymeen – Volume 1, Page 509
Question: I spend my day in Ramadhaan asleep or at rest since I am unable to work due to my [experiencing] severe pangs of hunger and thirst, so does this affect the validity of my fast?
Response: This does not affect the validity of the fast, [rather] therein is an increase of reward due to the saying of the Messenger (sal-Allaahu ‘alayhi wa sallam) to ‘Aa.ishah (radhi-yAllaahu ‘anhaa):
«Your reward is according to your hardship».
So, the more hardship a person experiences, the more his reward increases. He should [also] do what he can to reduce the effect of fasting such as cooling himself with water and resting in a cool place.