The Journal of neuroscience : the official journal of the Society for Neuroscience
March 18, 2026
Christine Blume, Marina Dauphin, Maria Niedernhuber et al.
During sleep, the human brain continues to process unexpected sounds, but the neural code becomes delayed, more redundant, and less rich as consciousness wanes. Twenty-nine participants heard an oddball sequence of tones while awake and during an 8-hour sleep opportunity. Prediction error responses occurred in all sleep stages (N1, N2, N3, REM). Mutual information analysis showed a substantial reduction in encoded prediction error information, especially during N3 and REM, even though electrical brain responses (ERPs) grew larger in deeper NREM sleep. Co-information analysis revealed that neural dynamics became increasingly redundant with deeper sleep. The neural code differed between wakefulness and sleep but was largely shared between N2 and N3 stages.
Clocks & Sleep
February 28, 2022
Angelina Birchler-Pedross, Sylvia Frey, Christian Cajochen et al.
Women with major depressive disorder (MDD) recall dreams as often as healthy women, but their dreams carry twice the negative emotional load, especially during the circadian night. In a controlled laboratory protocol, nine healthy and eight unmedicated women with MDD underwent ten alternating cycles of 150 minutes awake and 75 minutes asleep over 40 hours. Dream recall frequency did not differ between groups, but dream emotional load was significantly higher in the MDD group during nighttime naps. Higher negative emotional load in dreams correlated with worse mood in both groups. The findings suggest that circadian and sleep regulation of dreaming remains intact in unmedicated young women with MDD.
International journal of psychophysiology : official journal of the International Organization of Psychophysiology
August 1, 2013
Sarah Laxhmi Chellappa, Christian Cajochen
Dreams occur during both NREM and REM sleep, which are regulated by homeostatic, ultradian, and circadian processes. This review examines whether the ultradian NREM-REM cycle, gated by the circadian clock, influences successful dream recall, and identifies key electrophysiological correlates of dream recall during both sleep stages. It also explores age-related changes in the circadian and ultradian regulation of dream recall and its EEG correlates. Understanding the specific frequency and topographical EEG differences before dream recall may reveal the cerebral mechanisms underlying this cognitive process and their physiological significance.
Journal of Sleep Research
June 1, 2012
Sarah L Chellappa, Mirjam Münch, Vera Knoblauch et al.
Older adults show distinct brain activity patterns during sleep that are linked to whether they recall a dream. Compared with young people (20-31 years), older volunteers (57-74 years) had higher frontal delta and centro-parietal sigma activity during non-rapid eye movement (NREM) sleep before dream recall, but lower frontal-central delta and sigma activity before no recall. During REM sleep, older participants had less frontal-central alpha and beta activity regardless of recall. The findings suggest age-related differences in dream recall are directly tied to specific EEG frequency and brain-region patterns, especially during NREM sleep.
Biological Psychology
May 1, 2011
Sarah Laxhmi Chellappa, Sylvia Frey, Vera Knoblauch et al.
Dream recall is linked to distinct brain activity patterns during both NREM and REM sleep. In 17 young subjects under constant routine conditions, NREM sleep with dream recall showed lower EEG power density in delta frequencies, especially in frontal areas, and in spindle frequencies in centro-parietal areas. REM sleep with dream recall showed low frontal alpha activity and high alpha and beta activity in occipital areas. These frequency- and topography-specific EEG changes indicate that dream recall involves dual modulation across NREM and REM sleep, offering insights into the neural mechanisms of dreaming.
Sleep
September 1, 2009
Sarah Laxhmi Chellappa, Mirjam Münch, Katharina Blatter et al.
Dream recall declines with age, and this decline is linked to a weakened circadian rhythm of REM sleep. In a 40-hour nap protocol, 17 young (20–31 years) and 15 older (57–74 years) healthy volunteers reported fewer dreams after naps scheduled during the biological day, especially among older subjects. The number of dreams varied across the circadian cycle and between age groups, with older subjects recalling fewer dreams overall. No significant age differences appeared in the emotional content of dreams. The findings suggest that age-related changes in the circadian modulation of REM sleep contribute to reduced dream recall.