"He's obviously had a tough year on the ice and he needs, from a mental standpoint, needs to regroup basically," Wadell told Chip Alexander of the Raleigh News & Observer.
After struggling throughout the 2017-18 campaign, Darling has played just eight games for the Hurricanes this season, posting a 3.34 goals-against average and a .884 save percentage. He was placed on waivers Nov. 29 and has spent the majority of the campaign with the AHL's Charlotte Checkers.
"He had a tough game the other night and his agent called me and said he would like to take a personal leave of absence and would we allow that to get his mind back together," Waddell said. "That night he got rocked for about five (goals) and before he had a shutout (in regulation) before we lost in overtime 1-0. So we gave him the leave of absence."
Waddell added there is no set timetable for the 30-year-old's return.
"I'll touch base with him," he said. "I told him to take a week and touch base with me in a week or so and we'll go from there."
Carolina acquired the rights to the 6-foot-5 netminder in 2017 after his impressive three-year run as the Chicago Blackhawks' backup goaltender. Darling signed a four-year, $16.6-million deal to be the Hurricanes' starting goalie a week later.