Reciprocal relationships between sleep and smell

Abstract

Despite major anatomical differences with other mammalian sensory systems, olfaction shares with those systems a modulation by sleep/wake states. Sleep modulates odor sensitivity and serves as an important regulator of both perceptual and associative odor memory. In addition, however, olfaction also has an important modulatory impact on sleep. Odors can affect the latency to sleep onset, as well as the quality and duration of sleep. Olfactory modulation of sleep may be mediated by direct synaptic interaction between the olfactory system and sleep control nuclei, and/or indirectly through odor modulation of arousal and respiration. This reciprocal interaction between sleep and olfaction presents novel opportunities for sleep related modulation of memory and perception, as well as development of non-pharmacological olfactory treatments of simple sleep disorders.

Respiration-Triggered Olfactory Stimulation Reduces Obstructive Sleep Apnea Severity – A Prospective Pilot Study

“…We found that ‘Odor’ nights had lower wake index than ‘Control’ nights (‘Odor’: 1.9 (1.37), ‘Control’: 2.2 (0.7), Wilcoxon signed-rank test (12/17 patients): z = -2.0956, p = 0.0361, BF10 = 1.958, Fig 2d), and arousal scores (both cortical and autonomic), were not significantly different between the two nights (Arousal total sleep: ‘Odor’: 32.9 (26.12), ‘Control’: 26.9 (16.05), Wilcoxon signed-rank test (12/17 patients): z = -1.585, p = 0.113, BF10 = 0.855). These findings indicate that odor stimulation did not induce arousals and, in line with the literature 25 reduced the number of awakenings.…”

“…It is largely held that olfactory stimulation does not perturb sleep, and as discussed earlier, may promote it [24][25][26][27][28][29][30] . Nevertheless, in order to validate that in our experimental setting the olfactory stimulation did not arise from sleep, we compared the wake and arousal indices of 'Odor' and 'Control' nights.…”

“…Olfactory stimulation possesses a unique combination of traits that are particularly attractive for OSA treatment: First, purely olfactory and mildly trigeminal odorants (trigeminality is defined as the ability to stimulate the branch of the trigeminal nerve nested within the olfactory epithelium 18 ) do not wake from sleep [19][20][21][22][23] . Furthermore, evidence suggest sleep-benefiting effects for olfactory stimulation 24,25 during sleep, in health [26][27][28] and in clinical settings 29,30 . Second, and critically, despite not inducing arousal, incoming olfactory sensory information is picked up by the sleeping brain to influence physiology 19 , cognition 23,[31][32][33] , and most importantly in the case of OSArespiration 22,34 .…”

O cortisol associado ao sono REM e NREM: Uma revisão dos fatores que influenciam o período circadiano

“…O uso de aromaterapias está associado ao sono, já que a manutenção do sono pode ser influenciada pelo sistema sensitivo. Pode-se citar como exemplo a presença do cheiro materno, que é capaz de reduzir o choro e induzir os comportamentos para a alimentação no recém-nascido, o que acaba acelerando o processo de sono (Gaeta & Wilson, 2022). O mecanismo olfatório, que é capaz de regular o sono, está relacionado a circuitos neuronais em múltiplas interconexões, provocando assim uma modulação no processo de sono e vigília, além da uma estabilização.…”

“…É possível fazer uma análise de que os odores iram afetar e ativar o circuito noradrenérgico locus coeruleus e o núcleo dorsal da rafe serotoninérgica, que são componentes que podem induzir a liberação alta de cortisol durante as atividades. O uso de aromaterapia é dependente de uma especificidade, sendo uma associação entre o efeito que o odor é capaz de produzir na pessoa, parte biomolecular, e nas preferências e memórias associadas (Gaeta & Wilson, 2022).…”