Household smoke alarms reduce the chances of dying in a fire by up to 50 percent when present and working properly. However, studies have shown that the elderly do not fully benefit from smoke alarms, particularly during the overnight hours when they are asleep.

According to the National Fire Protection Association, older adults are more than twice as likely to die in a home fire as the average person.

The current study investigated arousal from sleep in 42 adults aged 65 to 85 years in response to various signals including the high-frequency signal used in most US smoke alarms, a mixed-frequency signal, and a male voice saying "Danger, Fire, Wake Up."

The high-pitched smoke alarm signal was least likely to wake the study subjects, Dorothy Bruck from Victoria University, Australia and the study team reports. The male voice also performed poorly.

The mixed signal was most effective in waking sleeping elderly.

The study also found that the volume needed to wake up to the high-frequency signal was significantly higher than that needed to wake up to the mixed-frequency signal.

"The high frequency alarm signal currently found in smoke alarms should be replaced by an alternative signal that performs significantly better in awakening most of the adult population, once the nature of the best signal has been determined," the authors recommend.

In the meantime, they encourage the use of interconnected smoke alarms that include an alarm in each bedroom to increase the chance of sleeping individuals being woken by an alarm.

The study also tested the performance abilities of older adults upon awakening suddenly to a smoke alarm. The results suggest a decrease in physical functioning of around 10 percent to 17 percent may be expected during the first five minutes after waking up. There were, however, "no important" effects on simple or complex cognitive functioning.