Sweet smells mean sweet dreams

Roses for sweet dreams, rotten eggs for nightmares

The smells in your bedroom as you drift off to sleep can directly affect the quality of your dreams, according to new research.

German scientists are reporting that when sleeping test subjects smelled the scent of rotten eggs, the nature of their dreams turned decidedly negative, while those luckier participants who were treated to the scent of roses had more positive dreams.

‘We were able to stimulate the sleeper with high concentrations of positively and negatively smelling odours and measure if the stimuli were incorporated into the dreams and changed the emotional tone of dreams,’ says Dr Boris Stuck of Heidelberg University, adding: ‘We found that the sleeper hardly ever dreamed of smelling something. Nevertheless, the emotional tone of the dream did change depending on the stimulation.’

As the 15 women who took part in the study entered rapid eye movement (REM) sleep where dreams occur, they were exposed to either a non-odorous control smell, the rose smell or the rotten egg smell. Each woman underwent three REM “awakenings” and were so exposed to each test smell once. Dreams were reported in 40 of the 45 awakenings. The women were then asked to describe the content of their dream on an emotional “colouration” scale that measured the tone of their dream. After the control stimulation, there was a slightly positive average colouration of 0.5; after the rotten egg smell, it was - 0.4 and after the rose smell the average was + 1.2 according to the study.

Professor Tim Jacob, an expert in smell and taste at Cardiff University told BBC News: ‘Smell is the only sense that doesn’t sleep. Information continues to reach the limbic system of the brian and that includes the hippocampus, or the memory area and the amygdala that is involved with emotional response.’