"I need eight hours of sleep every night."
Translation:Jag behöver åtta timmars sömn varje natt.
'timmars' - I haven't seen that before. How do you know when to use 'timmars' instead of 'timmar' for hours?
It is perfectly natural in UK English to say he got eight hours' sleep, or it is in three weeks' time. I think it is not just a Swedish construction.