Maybe it's the change in seasons, the lack of Vitamin D. The lack of sunshine. Maybe she is met to live in a sunshine state, but alas she has kids with dads and she can't just up and move them across country for that wouldn't be fair to either of the Dads nor the kids.
The world is great to her on a sunshine day, Summer is spent being overly happy and hyper but now as Winter is nearing, the days are shorter and darkness sets in earlier and earlier - she can't function. She wants to sleep. The kid isn't sleeping at night, except in her bed and she just is ready for her non kid weekend.
The non kid weekend brings people, family and catch up on work not completed during the week.She loves working and would lock herself in her office all of the time if the kids could only fend for their own self. Being felt as if there is a boulder on her head isn't good. This isn't who she is. What is wrong .. is it the change in seasons taking toll on her now in her older years?
She hopes for some much needed sleep without any disturbances so she can recoup and come back to her happy place and smile again.
Maybe if she puts up a Do Not Disturb sign and shuts off all electronics and phones she can just sleep a bit to recoup over her non kid weekend ... maybe sleep will help her to climb back up out of this funk.