Past Tense of "Dormir"
I'm having trouble wrapping my mind around whether the preterite or imperfect tense of dormir in this sentence would fit better: Esa noche los chicos dormían/durmieron pensando en todos los regalos que iban a recibir.
I would say both could be used equally, and that more context would be needed. To me the difference would be something like this: "Esa noche los chicos dormían pensando en..." - "That night the boys were sleeping thinking aboout..." and then something else possibly happened to interrupt their sleep, for example: "y de repente la ladrona entró en su habitación y blah, blah, blah". More used as background info. While "Esa noche los chicos durmieron pensando en.." - would be like "That night the boys slept thinking about..."- something you would use as a summary or reaction statement to a specific night.
It is for the one night, so it is one cycle of sleep. I would say use the Preterit.
Imperfect would be more along the lines of "my kid used to wet his bed in his sleep." Though there may be a different colonialism describing sleep when someone wets the bed, is that kind of concept that you would use the imperfect conjugation of dormir.
I would agree that the preterite would be the best choice
This may help - Study Spanish.com
Generally speaking, the preterite is used for actions in the past that are seen as completed. Use of the preterite tense implies that the past action had a definite beginning and definite end.
Juan habló de la una hasta las dos. Juan spoke from one until two o'clock. (clearly stated beginning and end)