The phrase "sleep nest" refers to a cozy and comfortable place where someone can rest or sleep. It basically means a welcoming and safe spot to relax and get some sleep. Full definition
Lack of sleep not only makes you ugly and sick, it also makes you dumb: missing shut - eye makes 6th graders as smart as 4th graders. (businessinsider.com)
We also finally stopped giving her her bottle at night and so she knows that bedtime is for sleeping not for eating and hanging out with mom and dad. (hintmama.com)
Sleep nest filling is made of 100 percent hypoallergenic certified polyester fiber. (momandbabylab.com)