The person sitting next to me in a shiur falls asleep because he worked hard during the day. What considerations are relevant to whether or not I should wake him?
Assuming I did not wake him and he remains asleep at the end of the shiur. What considerations are now relevant to whether or not I should wake him?
See, for example, Wikipedia “gezel sheina”
In Jewish law, gezel sheina (גזל שנה, theft of sleep) refers to waking up another person against their wishes. The term was first used by rabbi Israel Meir Kagan in his book Ahavas Chesed. No law in the Torah or Talmud directly prohibits disturbing another's sleep. Nevertheless, some rabbis have prohibited or discouraged such behavior as being unkind to others and because it cannot be rectified.