The psychedelic substance psilocybin causes transient changes to the sleep-wake architecture of laboratory mice, according to new preliminary research published in Translational Psychiatry. The findings provide new details about how the drug impacts sleep-related brain activity.
“There is evidence that, under the right circumstances, psychedelic drugs such as psilocybin can rapidly alleviate core symptoms of diverse psychiatric illnesses, for example depression, even in severe cases which are resistant to current treatments,” said study author Vladyslav V. Vyazovskiy, a professor of sleep physiology at the University of Oxford. “But the neurophysiological mechanisms underlying the beneficial effects of psychedelics are unknown.”
Vyazovskiy and his colleagues were interested in examining psilocybin’s potential impacts on sleep because “sleep disturbance contributes to both the onset and continuation of many mental health conditions,” he explained. Animal models can help to better understand the mechanisms underlying psilocybin’s effects on sleep.
“The possible interaction between sleep regulation and the effects of psychedelic compounds has received very little attention despite the fact that there are shared mechanisms in the underlying biology, such as serotonin signalling and synaptic plasticity,” Vyazovskiy said. “Sleep is rarely if ever considered as a potentially important factor that can affect the response to psychedelics, which is surprising given that sleep is often disrupted in mood disorders”
For their study, Vyazovskiy and his colleagues implanted mice with electrodes before injecting them with psilocin (the metabolite of psilocybin) and monitoring their sleeping patterns.
After receiving psilocin during a time when the mice typically slept, the researchers observed that the animals struggled to reinitiate sleep. “Psilocin-affected mice spent a significant amount of time in their nests, adopting a posture compatible with sleep, but still apparently awake according to electrophysiological criteria,” they explained.
The researchers also found that psilocin delayed the onset of rapid eye movement (REM) sleep and reduced the maintenance of non-rapid eye movement (NREM) sleep for up to three hours after dosing. “This form of sleep disruption resembles an increased propensity for brief awakenings, usually defined in mice as periods of wakefulness lasting ≤ 20 seconds occurring during NREM sleep and typically accompanied by small body movements,” they wrote. But sleep-wake activity appeared to return to normal after approximately 4 hours.
“We see changes in sleep states and brain activity during sleep after exposure to psychedelics, which can inform us about the underlying neurophysiological mechanisms of psychedelic action,” Vyazovskiy told PsyPost. “Sleep is an essential part of physiology, it shouldn’t be neglected when thinking about health, particularly in the brain.”
The findings are in line with a previous study in humans, which found that psilocybin delayed the onset of REM sleep, the stage of sleep in which most dreaming occurs, on the first night after administration.
The new study offers more clues about how psychedelic substances influence sleep activity, but more research is still need. “Our study was conducted in animals, and so whether similar effects occur in humans is not known,” Vyazovskiy noted. “Furthermore, the animals were ‘normal’ (we did not look in any model of psychiatric illness) so we also do not know how the presence of sleep disturbance of the kind seen in mental health disorders might affect the brain’s response to psychedelics.”
“It remains to be studied whether the relationship between sleep and psychedelic effects are bidirectional,” he added. “For example, we should address the possibility that sleep has an important role in consolidating the beneficial psychological effects of psychedelics and is important for long-term recovery from mental illness. Also, the possibility that there are circadian effects on the response to psychedelics (related to your body clock) has not been studied, and should receive attention in future research.”
The study, “Psilocin acutely alters sleep-wake architecture and cortical brain activity in laboratory mice“, was authored by Christopher W. Thomas, Cristina Blanco-Duque, Benjamin J. Bréant, Guy M. Goodwin, Trevor Sharp, David M. Bannerman, and Vladyslav V. Vyazovskiy.