Can we smell in dreams?

Question

I'm interested in whether people can smell in their dreams. Do people really experience smell in their dreams? For example, if I dream of smelling a flower, will I feel the smell, too?

Is there any research on whether people can smell in dreams?

Answer 1

Antonio, Nielsen and Doneri (1998) provide one assessment of self-reported prevalence of smell in dreams. To quote the abstract (my bolding):

Although numerous studies have investigated the content of laboratory and home dream reports, surprisingly little is known about the prevalence of various sensory modes in dreams. 49 men and 115 women completed a battery of questionnaires and kept a home dream diary for two to three consecutive weeks. Retrospective responses to the questionnaire indicate that approximately 33 % of men and 40% of women recalled having experienced sensations of smell or taste in their dreams. A total of 3372 dream reports were collected and scored for unambiguous references to auditory, olfactory, and gustatory experiences. Auditory experiences were reported in approximately 53% of all dream reports. Olfactory and gustatory sensations occurred in approximatdy 1 % of all dream reports. A significantly greater percentage of women than men reported one or more dreams containing references to olfactory sensations. The results lend support to previous studies which have shown that a variety of sensory experiences, although rdativdy rare, can occur in dreams.

There is still the question about whether self-reports are trustworthy, and how you define a smell experience in a dream that is most likely not generated by external stimuli. Antonio and colleagues go on to discuss some of these issues:

That the more infrequent modalities of smell and taste occur at all in dream reports is an important indication of the representational capacities of dreaming-and probably of imagery more generally. The finding is consistent with recent research showing the existence of imagery in both olfactory (Carrasco & Ridout, 1997; Lyman & McDaniel, 1986) and gustatory (Drummond, 1995) modalities. Although some researchers take the position that olfactory imagery is not possible (Herz & Engen, 1996), the spontaneous occurrence of olfactory imagery in dreams may differ from "willful" olfactory imagery that may occur upon instruction during the waking state. For instance, limbic structures which might yield such spontaneous occurrences during dreams may not be operational during the waking state. Nevertheless, it is likely that the relatively rare occurrence of these modalities during dreaming is not because their representation is beyond imaginal capacity. Rather, either such sensations are not usually spontaneously generated during dreaming, i.e., are not a necessary component of dreaming's supposed memory/adaptational functions, or they depend upon external sensory stimuli to trigger them. However, sensory triggers may be selectively blocked at the thalamic level by the raised afferent thresholds of REM sleep (e.g., Steriade, 1994). Of course, both of these inhibiting conditions may be true, thereby seriously disfavoring appearance of gustatory or olfactory sensations during dreaming

References

• ANTONIO, L.Z. and Nielsen, T.A. and Donderi, DC. (1998). Prevalence of auditory, olfactory, and gustatory experiences in home dreams. Perceptual and motor skills, 87, 3, 819-826.PDF
• Carrasco, M., & Ridout, J. B. (1997) Olfactory perception and olfactory imagery: a multidimensional analysis. Journal 0f Experimental Psychology: Human Perception & Performance, 19,287-30l.
• Drummond, P. D. (1995) Effect of imagining and actually tasting a sour taste on one side of the tongue. Physiology & Behavior, 57, 373-376.
• Herz, R. S, & Engen, T. (1996) Odor memory: review and analysis. Psychonomic Bulletin & Review, 3, 300-313
• Lyman, B. J., & McDaniel. M. A. (1986) Effects of encoding strategy on long-term memory for odours. Human memory. Quarterly Journal of Experimental Psychology: A-Human Experimental Psychology, 38(4-A), 753-765.
• Steriade, M. (1994) Brain electrical activity and sensory processing during waking and sleep states. In M. H. Kryger, T. Roth, & W. C. Dement (Eds.), Principles and practice of sleep medicine. (2nd ed.) Philadelphia, FA: Saunders. pp. 105-124.

Answer 2

Also, in Oliver Sack's The Man Who Mistook His For His Wife, the author and famous neurologist reports a case about a man who dreamed he had the olfactory powers of a dog; however, when he awoke, he still retained his heightened sense of smell and furthermore could prove it to the nurses.

Any experience that one has in waking life can be recapitulated during a dream. In addition, Anthony Wagner has a line of research investigating how rehearsal and learning mechanisms operate during sleep. It is unclear at this point how much novel learning can occur during sleep, as no paradigm has demonstrated this very successfully.