Jake Epping visits his friend Al one day to find him on deaths door, whereas the day before, he was completely healthy. What explanation is given for his sudden lack of health?

Al’s sudden lack of health is explained by the fact that he spent four years beyond the time portal, during which his lung cancer progressed dramatically. To Jake, only about a day had passed; for Al, years of aging and illness had occurred before he returned to the present.

In Stephen King’s 11/22/63, Al Templeton discovers a portal in the pantry of his diner that always leads to the same moment in the past. He initially uses it for practical advantages, but eventually spends years in the late 1950s and early 1960s researching Lee Harvey Oswald and planning how to prevent President John F. Kennedy’s assassination.

The apparent overnight illness is therefore a time-travel effect, not a new disease appearing instantly. Al had already been diagnosed with terminal lung cancer and had endured years of its progression while living in the past. His heavy smoking history is also associated with the cancer, but the key explanation for Jake’s shocking discovery is the years Al experienced beyond the portal.

A common mix-up is to attribute Al’s condition to radiation sickness or an unusual side effect of time travel. The portal changes the amount of time a person experiences, while only minutes pass in the present; it does not give Al radiation poisoning.