床(chuáng) - bed in Mandarin

床 is the ordinary word for a bed. Its measure word is 张, the same one used for flat things like tables and sheets of paper, so a bed is 一张床 and never 一个床.

Two very common compounds carry most of the everyday load. 起床 is to get up, literally to rise from the bed, and it is what you use for getting out of bed in the morning rather than 起来 on its own. 上床 is to go to bed, though be aware it also has the euphemistic sense of sleeping with someone, so 睡觉 is the safer verb if you just mean turning in.

The location phrase is 床上, on the bed or in bed. English says in bed and on the bed for different things; Chinese uses 床上 for both and lets context sort it out.