I feel this, but it's only one kid for me. Three must be insane. Most days I look forward to something intended to occupy that free time, but like you I'm always wiped or experiencing a headache by 8pm or later. So I've gotten back into reading. Low energy, comfy, can do it on bed. Except now I open the book and am nodding off between sentences. Falling asleep easier than ever, but doomed nonetheless.