Hello and hope you are doing well.
Her symptoms could be due to sleep apnea. This is becoming more common in children. Overweight children are more prone for apneic episodes. Also tonsillar enlargement or adenoids can cause narrowing of the air passages leading to apneas in sleep. I would advise you to discuss her symptoms with your primary care physician who may then refer her to a sleep specialist for further evaluation.
Hope this helped and do keep us posted.
Honestly that sounds like sleep apnea. You should talk to your pediatrician to see if they can do a sleep study, this will determine if she does have sleep apnea and if she's getting enough oxygen while asleep. With sleep disorders you genuinely have cranky children, a little slow to get going. Does she seem to have less energy than others her age and still like getting in a nap? Does she complain of headaches?
There are several other things that could have similar symptoms but another that comes to mind is allergies and asthma. If a person is allergic to dust mites, dust, or feathers a bed can be a nightmare. Also if she was out playing outside/with animals and is allergic to that she is basically spending hours laying in that allergen. Does she ever "itch" her nose with her hand like there is something on it or constantly have scratchy throat, runny nose, etc? If so you may want to consider an allergy test.
So talk to her doctor, it's important for her to get sleep. It's also important to rule out anything serious. Ask him about sleep apnea in children as well as other sleep disorders and the possibility of getting an allergy test.