The Australian Open quarterfinalist said she needs a break after six months away from home as she attempts to return to the highest levels of the sport.
Essentially out of tennis in 2007, Dokic played four WTA tournaments last year and won three titles on the ITF circuit. But the campaign is taking its toll.
She said she is "having a hard time figuring out what to do on the court right now" and said she may have been mentally beaten before taking the court against Craybas.
"I'm really, really struggling mentally," said Dokic, 26. "I need to just settle down and get myself together again."
Dokic, who also represented Australia in the Fed Cup recently, said she could return for the Sony Ericsson Open in Miami starting March 25.
In other early first-round matches Wednesday, Shahar Peer beat Kateryna Bondarenko 6-2, 6-1; Nicole Vaidisova overcame Michaella Krajicek 6-3, 6-4; and American Alexa Glatch bested Stephanie Dubois of Canada 6-3, 6-2.