It's a major risk factor facing firefighters, work-related heart attacks.
But a new study out of Beloit could help reduce that job hazard. It shows ramped-up tones keep heart-rates from climbing to extreme highs.
"We looked at the startle response and we looked at ways to gently wake them as opposed to suddenly waking them," Dr. James MacNeal said.
The Mercy Health Systems doctor also serves as Beloit Fire's Medical Director. He published the findings with Yale University researchers last month, in the Journal of Occupational and Environmental Hygiene.
Dr. MacNeal recorded the heart rates of roughly 30 Beloit firefighters, both at rest and after the tones.
"We've got pretty clear evidence that this works," he said.
Beloit's Deputy Chief Joe Murray agrees. He says the non-interval tonesput his firefighters on edge.
"I would wake up and the tones would go off in the middle of the night, it felt like my heart pounding it felt like it was coming out of your chest," Deputy Chief Murray said.
But now that memory is just a bad dream, he says the ramped up alarms make a world of difference.