Sadie Lachlan, 52, was discovered by staff when she failed to come out of the private booth at the premises.
Workers raised the alarm when the mother-of-two overran her allocated slot at Tanz in Carluke, Lanarkshire. Paramedics rushed to the scene to administer emergency treatment to Mrs Lachlan but were unable to revive her.
The tragedy happened around 11.50am on Monday after the mother, of Carluke, had gone to the salon to top up her tan.
Police Scotland and health and safety officials have launched an investigation.
A post-mortem is due to be carried out but the death is not being treated as suspicious. The company, who are based in nearby Motherwell, refused to comment.