The Smell of Sleep & Dreams

A new study examined how your sense of smell may affect your dreams.

The small study from Germany involved 15 volunteers. They were studied using sensory stimulation during the sleep stage of rapid eye movement sleep – or REM sleep.

The study compared two smells with a control condition. One smell involved hydrogen sulphide – the smell of rotten eggs. The other smell involved phenyl ethyl alcohol – the smell of roses.

Results show that the “olfactory stimuli” significantly affected the emotional content of dreams. The smell of roses yielded dreams with a more positive tone; the smell of rotten eggs was followed by dreams that had a more negative tone.

But the smells were not directly included in the dream content; volunteers did not dream about smelling a rose or rotten eggs.

The authors report that smells are unlikely to wake you from sleep; so olfactory stimulation is likely to be included in dreams as the sleeping brain processes sensory information.

The authors conclude that it would be interesting to study the effect of pleasant smells on nightmares.

Image by Joe Penniston