Alarm clocks for the deaf apparently work on the principle of vibration - you've got a clock hooked up to a disc or pad that slips under your mattress, and it literally shakes you awake when it's time to get up. (I think I'd opt for one of the vibrating wristwatches, myself.)
Japanese researchers have just come up with a possible alternative strategy: smell. In particular, the smell of wasabi.
A new type of fire alarm in Japan has been developed using the pungent smell of horseradish.
The device is drawing attention as a new way to warn people with hearing disabilities.
Medical equipment manufacturers have developed a technology to extract components of the strong odor of horseradish, seal them inside a can and spray them out.
Shiga University of Medical Science Hospital cooperated with the makers and carried out experiments to see if the horseradish smell can wake up people from a deep sleep.
Fourteen people, including those with hearing disabilities, took part in the experiments.
In the experiment, 13 out of the 14 subjects woke up in less than two minutes after the smell reached their noses.
The people with hearing disabilities were particularly quick to wake up, with one person emerging from sleep in just 10 seconds.
I wonder if the sleepers awoke craving sushi.