As an English person, I would not use the phrase 'snarled up' in reference to bedding or hair, etc. I believe this is a term mostly used in America. However, they way you have used it is correct. Snarled can also mean the past tense of snarl, like a growl, so when talking about bedding I would use the phrase 'snarled up' Extra tip: you can use the word 'tangled' instead of snarled when talking about something being all twisted up on itself. Hope this helps. :)