An Indiana teen accused of sexually assaulting a 15-year-old girl claims that he suffers from a rare, but legitimate condition called “sexsomnia.”

Andrew Passwaiter, 18, told police that he was diagnosed with the condition, which causes people to engage in sexual behavior while asleep, but not remember it. He was arrested on Monday for an incident that occurred in early March.

The 18-year-old from Blooomington, Indiana said that he does not recall fondling the girl during a sleepover, according to KCTV.

The victim claimed that Passwaiter put his hands down her pants in the middle of the night while she was sleeping and woke her up.

According to police, Passwaiter told them the doctor who diagnosed him as a sexsomniac had died.

“He stated that he had been diagnosed but was unable to provide us with any information of a doctor we could follow up with,” Bloomington Capt. Steve Kellams told KTCV.

The 18-year-old faces charges of sexual battery, and would need to prove in court that he has a history of sexsomnia.

There is not much research about the rare disorder, but a study at the Toronto Western Hospital in Canada found that 7.6 percent of sleep center patients suffered from symptoms of sexsomnia.