Rising
Getting Out Of Bed
noun, verbal noun, の adjective
Wake up from your bed and get up. You are rising or getting out of bed.
The readings are the on'yomi readings for both of these. For 起, just remember how in order to get up out of bed, you have to be let out of your chains, which requires a key (き). Otherwise, you stay laying down forever.
彼は起床時間になっても、まだいびきをかいています。
He is still snoring even though it’s time to get out of bed.