A cat sleeping curled up in a ball may indicate abdominal pain or that your cat doesn't feel well.
An unwell cat sleeping on their side with legs extended could mean they are having breathing issues.
When a cat isn't feeling well they may sleep stretched out on their belly to cool down if feverish.
Frequent position shifting during sleep could signify your cat is uncomfortable due to illness.
A sick cat that sleeps hidden away from you may feel instinctually vulnerable.
Though unusual, a cat sleeping belly up when sick may be trying to relieve pressure on lungs or abdomen.
Any sudden change in your cat's typical sleep positions while ill is worth monitoring closely.