keep sb + 动词的过去分词 是什么用法,什么意思,为什么要用过去分词

Keep it done 有类似 get it done/have it done的用法,但还有keep getting things done的形式,keep用于保持或持续某种状态,较为用于形容动作
如：There are many ways to keep your hair done while sleeping and have your hair the same as the day before.有许多方法能让你的头发在睡觉的时候还能和白天一样（形状等）.