Gillian Polack 
The Art of Effective Dreaming [EPUB ebook] 

Fay invented a world of fantasy where she could dwell in happiness. Her friends in this perfect world were Belle and Persa, Enlai and Flor. She visited them on the edge of sleep, shaping their lives to suit herself.
‘I dream better than other people. More efficiently and effectively, ‘ she explained to herself. Her dreams were a flicker away from reality.
After Gilbert turns up in her refuge, undesigned, unheralded, and disturbing, Fay’s dream world shatters. But are her dreams really dreams, and should she leave her friends behind and live in the real world?