The study was carried out on six participants in their twenties. Two different scents were used, the sweet, pleasant aroma of peppermint and pyridine, a pungent liquid and the by-product of fire.
Participants detected both aromas when awake and in the early stage of sleep. After dropping down into the deeper sleep levels, however, no one reacted at all to the odor of peppermint. There were some infrequent minor reactions to the pyridine, but no one awakened.
The auditory sense, however, does respond during sleep. Even a moderately loud noise aroused the study group every time.
Why is this true? The study suggests a "significant alteration of perceptual processing as a function of sleep." Olfactory perception, or the sense of smell appears to be practically nonexistent during sleep.
Many people rely on their sense of smell to awaken them in the case of fire. This study warns that this is not a reliable alarm system, which is probably why so many lives are lost every year in night time fires. People continue to sleep while the room fills with smoke or their mattress goes up in flames around them.
Why take the risk? Smoke detectors are cheap, generally reliable and might just save your life. Every house should be equipped with several, especially in sleeping areas. The battery type should be checked and the battery changed regularly.
