"Bjørne sover om vinteren."

Translation: Bears sleep in the winter.

[Mae-Rose]

Why is it om rather than i here?

[Xneb]

Om is used when referring to specific time periods (with the exception of months, which use i)
For example: Jeg rejser til Danmark om en uge (I'm travelling to Denmark on Monday)
Jeg rejser til Danmark i December (I'm travelling to Denmark in December)

[SenThomson]

Is there a reason "bears sleep for the winter" is not currently accepted?
(20/05/2020)

[hestvang]

why not 'over winter', itøs a time period so in English 'over' is acceptable as in 'a sleep over' not 'a sleep in' which is entirely different.

[Jana63110]

Or during the winter?