Sleeping with One Eye and Ear Open

All week I've been spending the day at my mom's to help with anything she needs: cleaning dishes, moving things, getting her food, and other basic needs.  I've also been here just in case she falls - that way she has someone on site to help right away.  At night one of my brother's stays the night as he works in town during the week so he just stays with her.  On the weekends he returns home.  So, tonight is my first night to stay the night at my mom's house in a long time, and it's the first time staying with her ability to move around being so difficult.    I am pretty nervous.  She says she gets up 3-4 times a night.  What if she falls and I don't hear it?  Well, I wouldn't be able to stomach that so I'm just gonna sleep with one eye and one ear open.