No Sleep Till Wonderland by Paul Tremblay

Narcoleptic Southie PI Mark Genevich returns in this sequel to The Little Sleep from the Bram Stoker Award-winning author of Survivor Song and The Cabin at the End of the World.

Like most private eyes, Mark Genevich is something of a lone wolf. So group therapy isn't a great fit. But his landlord/mother is convinced it will help his narcolepsy-ignoring the fact that his disorder is a physical condition. Truth is, he has the time. It's been a year and a half since his last big case, or any case.
It's never a wise choice to go on a two-day bender with someone you meet in group therapy, but there's something about Gus that intrigues Genevich. And when his new drinking buddy asks him to protect a female friend who's being stalked, the PI finally has a case.
Unfortunately, he's about to sleepwalk right into a very real nightmare. Before long he's a suspect in an arson investigation and running afoul of everyone from the cops to a litigious lawyer and a bouncer with anger management issues. Genevich must keep his wits about him-always a challenge for a detective prone to unexpected blackouts and hallucinations-to solve the crime and live to show up at his next therapy session.
In Paul Tremblay's follow-up to The Little Sleep, unreliable narrator Mark Genevich once again leads readers on a surreal and suspenseful wild ride through the mean streets of South Boston and his own dreamlike reality.