Angel: Stranger to the Sun (Buffyverse Novel #61) by Jeff Mariotte

Even if it takes an eternity, he will make ammends...

NEVER-ENDING NIGHT

When Wesley opens a package that arrives special delivery, he is instantly sent into a coma-like slumber. It's obvious he has fallen victim to a spell, and Angel sets off with Gunn to get to the bottom of things. But everyone in a position to assist -- magick-shop owners and even traditional authorities like policemen -- have also been hit by the supernatural sandman.

Cordelia, meanwhile, is on research duty, which is harder without Wes around. Some of his colleagues have clued her in to a plot -- vampire, natch -- to plunge the Earth into constant darkness, so that they might reassert their power without fear of daylight. She wants to help prevent this, but while she tends to Wesley it becomes clear that he is in the throes of a terrifying nightmare. If she can't rouse him, it may be the end--for him, as well as the rest of humankind...