shivering mimetic word: ブルブル
space out, daydream, stare off into space:ぼーっとする (written in kana alone)
sleeping soundly onomatopoeia: すやすや
This image was created by me, but has been checked by a native speaker for accuracy (Hajime Maeda, check out his tumblr). Please feel free to share* the image, if you do please link to my blog. Thanks!
*but not sell