It was the middle of the night __ my father woke me up and told me to watch the football game .A.that B.as C.which D.whe

It was the middle of the night __ my father woke me up and told me to watch the football game .A.that B.as C.which D.when
为什么这里要when不用that,用that不是一样可以当做强调句型来理解吗?the middle of the night 直接做状语不行吗?