Eric “Rick” Ylagan, a respected Bangor High School earth science teacher and coach of that school’s state championship boys tennis team, died in his sleep early Saturday morning at his home in Brewer, apparently of natural causes.

He was 39.

“It’s just a complete shock to all of us,” Bangor High School athletic director Steve Vanidestine said. “I saw him at school Friday and he was the picture of health.”

According to Brewer police records, emergency medical personnel were called to Ylagan’s home in Brewer at about 2:40 a.m. Saturday. Upon their arrival, they found Ylagan’s sister, Elizabeth Ylagan, performing cardiopulmonary resuscitation. Ylagan was taken to Eastern Maine Medical Center, where he was pronounced dead.

Bangor High School Principal Norris Nickerson said plans were put into place over the weekend to make grief services and other support available to students and staff who need them. Nickerson said while he had been able to contact most of the teaching staff at Bangor High, he was concerned that news of the death might come as a shock to students.

“He was an excellent and energetic teacher,” Nickerson said. “This was completely unexpected. He was very athletic.”

Shawn Yardley, whose sons Josh and Jeremy Yardley both played tennis for Ylagan, said the boys from last year’s Class A state championship team have plans to meet on the Bangor High tennis courts after school Monday. Jeremy Yardley played third singles for the championship team.

Jeremy Yardley had just played tennis with Ylagan Friday. The family kept in touch with the coach even though both Yardley brothers have graduated.

“We weren’t close socially, but he was a part of our family because of the role he played in our kids’ lives,” Shawn Yardley said. “… I know he was excited to go into this season as the defending state champion. This is a terrible loss.”

He is survived by his wife Wendy, daughter Sidney, 6, son Shane, 3, and other family members.

“I’d like [Ylagan’s children] to know that their father was such a good man,” Yardley said.

Vanidestine described Ylagan as an educator who set high standards for his students, both academically and in terms of conduct.

Ylagan took over the Bangor High boys tennis program in 1997. He was named the 2002 Penobscot Valley Conference Coach of the Year for Classes A and B. He also coached both the boys and girls tennis teams until separate coaches were provided for those teams and briefly coached the school’s field hockey team.

Ylagan, a native of Ann Arbor, Mich., was a 1985 graduate of Rutgers University in New Jersey. He earned a master’s degree in environmental education from Audubon Expedition Institute in 1988. He taught earth science in New Jersey for six years before moving to Maine.

In addition to his years at Bangor High, Ylagan taught geology, astronomy and kayaking at the Maine Audubon Sanctuary on Hog Island, where he met his wife.

Friends may call from 7-9 p.m. Tuesday at Brookings-Smith in Bangor. A funeral service will be held at 11 a.m. Wednesday at the Unitarian Universalist Society of Bangor. Gifts in Ylagan’s memory may be sent to the Eric E. Ylagan Scholarship Fund, in care of Key Bank, 29 Bangor Mall Boulevard, Bangor, Maine, 04401.

Sportswriter Jessica Bloch contributed to this story.