She could have Gapeworm, though this would not explain her sleep behavior. If no other symptoms appear, I'd worm with Safeguard or Fenabenzole.
 
However, these could also be the early stages of a respiratory infection. If other symptoms, like sneezing, coughing, swelling of the face, or heavy breathing become present, start her on antibiotics. Oxytetracyline is a good antibiotic to start with. If it doesn't work, get Tylan200 (dosage is .5 ccs for large fowl, .1-.3ccs for bantams) or Tylan50 (dosage is 1cc for large fowl, .5ccs for bantams). 
 
It could be a viral respiratory disease, in which case an antibiotic will not work. All you can do is keep her warm, hydrated, and well fed. Give her probiotics,  electrolytes, and vitamins. She may lose her appetite, in which case you can try to entice her into eating by offering her yogurt, scrambled eggs, and applesauce. Moistened chicken feed might also be enjoyed.
 
Good luck!