The Emerald of Viridian by Claire Norsworthy
When she's awake, nobody sees her.
When she sleeps, they all come out to kill her.
Katie Edwards only wants one thing—gorgeous and popular Jake Bronson. After a crushing rejection when she asks him to the Sadie Hawkin's dance, Katie goes to bed that night, humiliated and heartbroken, knowing she no longer wants to remain the same. The night of this revelation, she falls asleep in her bed, but wakes up in an island paradise that is very, very far from Earth.
After surviving several near-death experiences in the tropical jungle, she awakens again in her bedroom, as if Viridian were only a dream.
Or was it real? Her misadventures steel her resolve to change and improve, especially when she senses something lurking in the shadows, watching her every move. Katie pushes herself to run, lift weights, and learn to fight. That way, when her Viridian dream-life takes her to a place far from home and full of danger, she is strong enough to stand up against her enemies.