Compare during and for:
I fell asleep during the film. I was asleep for half an hour.
– Use FOR + a period of time to say how long something goes on: for two hours, for a week, for ages… Example: We watched television for two hours last night.
– Use DURING + noun to say when something happens (not how long): during the film, during our holiday, during the night… Example: We bought nice souvenirs during our holiday.
Remember!! You cannot use during to say how long something goes on: It rained for three days without stopping. (NOT during three days).
– With ‘time words’ (the morning, the afternoon, the summer…), you can usually say in or during. Example: It must have rained in the night (or during the night).
(Source: English Grammar in Use. Cambridge)