Check out the book: Healthy Sleep Habits, Happy Child by Weissbluth.
BTW, I noticed my older daughter getting super cranky when using iPads/phones when she was about 2.5, so we stopped giving them to her and her mood vastly improved as a baseline. You’ll have to make your own decisions about tech and kids, but just keep that in mind. My kids now will happily go on a 12 hr car ride without ever asking for an iPad, etc. YMMV.