In a recent study published in Scientific reports, researchers have discovered links between the psychoactive effects of classic psychedelics and patterns of brain activity that resemble those observed during sleep. The results suggest that psychedelics induce a unique state that integrates wakeful behaviors with sleep-like brain waves.
Classic psychedelics, including compounds like 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT), are known to induce profound changes in perception, emotion, cognition, and movement. These substances, structurally similar to serotonin, have been the subject of interest due to their potential therapeutic effects and their ability to produce dream-like states. However, the exact brain mechanisms underlying these effects remain largely unknown.
“As a sleep and memory researcher, I have been interested in psychedelic states as waking proxies of dreaming,” said study author Sidarta Ribeiro, a full professor of neuroscience at the Brain Institute. from the Federal University of Rio Grande do Norte, research associate of the Center for Strategic Studies of the Fundação Oswaldo Cruz (FIOCRUZ), and author of The Oracle of the Night.
“We have already discovered that psychedelics can induce neuroplasticity similar to that induced by sleep. This sparked our interest in assessing neural markers of slow-wave sleep (SWS) and rapid eye movement (REM) sleep after administration of 5-MeO-DMT, a potent classical psychedelic.
Slow-wave sleep (SWS) is a deep stage of sleep characterized by slow, high-amplitude brain waves called delta waves. It’s crucial for physical restoration, memory consolidation, and overall brain health. Paradoxical eye movement (REM), on the other hand, is marked by low-amplitude, mixed-frequency brain activity, similar to a wakeful state, and owes its name to rapid, random eye movements. REM sleep is essential for emotional processing, learning, and memory, and it’s when most dreams occur.
The researchers conducted their study on 17 adult male rats. These animals were housed under controlled conditions and subjected to a series of experimental sessions. The focus was on the acute effects of 5-MeO-DMT, a psychedelic compound, on brain activity.
To study this, the team used electrodes to record brain activity from two key areas: the medial prefrontal cortex (mPFC) and the hippocampus (HP). These regions are crucial for cognition and navigation, respectively. The electrodes were carefully implanted into the rats’ brains, allowing detailed monitoring of electrical activity.
The experimental design involved administering different doses of 5-MeO-DMT or saline (as a control) to rats and then recording their brain activity and behaviors. The recordings were made while the rats were moving freely in an arena, which provided a naturalistic setting to observe the effects of the drug.
Rats exhibited a range of altered behaviors after receiving 5-MeO-DMT. These included uncoordinated movements, periods of immobility, and stereotyped behaviors like head twitching.
The researchers found that 5-MeO-DMT induced notable changes in brain wave patterns, particularly in the hippocampus. Theta waves, which dominate during active behavior and REM sleep, showed a significant decrease in their strength after drug administration. This was not solely due to changes in the rats’ moving speed, suggesting a direct effect of the drug on brain activity.
Researchers also discovered changes in gamma waves, which are associated with higher brain functions like attention and memory. Slow and medium gamma oscillations were affected, with a reduction in their power and dose-dependent modulation by theta waves. This indicates that 5-MeO-DMT modifies the complex interaction between different brain rhythms.
Using a technique called state mapping, which traces patterns of brain activity, the researchers observed that 5-MeO-DMT induced transitions between waking and sleeping states. Even though the rats were awake and moving, their brain activity resembled that of sleep states, particularly slow-wave sleep (SWS) and REM sleep. This suggests that the drug creates a hybrid state combining elements of wakefulness and sleep.
“We were quite surprised by the fact that the transition probabilities between states as defined by brain waves, that is to say the chances of moving from one state to another, were not significantly changed after administration of 5-MeO-DMT, despite the fact that the animals were obviously awake, moving around, and engaging in stereotyped behaviors,” Ribeiro told PsyPost.
“The take-home message from our study is that rats will be openly awake after administration of 5-MeO-DMT, and yet their brain waves will show the continuation of the sleep-wake cycle. We suspect that this may underlie the existence of psychedelic substates in which rats (and presumably humans) are more extroverted (wake-like) or introverted (sleep-like). In addition, these introverted states can present in two forms, one more sleepy (SWS type) and the other more dreamlike (REM type).
The findings provide new insights into the complex effects of psychedelics on the brain. Rats have a brain structure that, although simpler, shares many functional similarities with the human brain. These similarities allow researchers to draw parallels between the functioning of the rat and human brains and draw conclusions about how psychedelics might affect the human brain.
However, results obtained in rats may not be fully translatable to humans due to species-specific differences in metabolism, receptor distribution, and overall physiology. “Rats are not humans, so we cannot directly assess their subjective experience,” Ribeiro noted. He plans to “follow up these findings in human subjects and then explore in detail the characteristics of each of these three psychedelic substates (wake-like, SWS-like, and REM-like). »
“It is time for psychedelics to be fully legalized and freely studied,” Ribeiro added.
The study, “5‑MeO‑DMT induces sleep-like LFP spectral signatures in the hippocampus and prefrontal cortex of awake rats,” was authored by Annie C. Souza, Bryan C. Souza, Arthur França, Marzieh Moradi , Nicholy C. Souza. , Katarina E. Leão, Adriano BL Tort, Richardson N. Leão, Vítor Lopes-dos-Santos and Sidarta Ribeiro.