Police say a man whose name has not been released returned home from a weekend away to find his girlfriend, Rhonda Waits, 46, lying in the bed unresponsive, KXAS-TV, Dallas, reported.
He called authorities, who went to the house at about 12:17 a.m. Sunday and reported finding no sign of trauma, WFAA-TV, Dallas, said.
The tanning machine was equipped with a timer that switches off after a selected time is reached. It was not on when the woman's body was found.
The Tarrant County medical examiner has not released an official cause of death.