In a record store in downtown Detroit, a radio DJ was starting to lose the plot. The 27-year-old was the star attraction of a nine-day fundraiser for muscular dystrophy, spinning discs, entertaining customers with his spiel and shooting pool. Outwardly all seemed well until the third day, when without warning he flew off the handle, pulling on his coat and shouting: “You’re all trying to make a fool out of me! I’m quitting!”


He changed his mind, but over the next few days he became increasingly paranoid and irascible. On the evening of the sixth day his mood turned grandiose: he announced that he would take on “every DJ in the US” in a competitive fundraiser in the window of a famous Detroit department store. By the following morning, however, euphoria had given way to exhaustion.

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Then the hallucinations began. He saw flames spurting from the walls and a grey mist hanging over the pool table. One moment he was floating on a black cloud surrounded by the indistinct forms of ballet dancers, the next he was broadcasting live from the scene of a fire elsewhere in the city.

By the ninth day he could barely speak or walk. He collapsed and was rushed to hospital where he fell into a deep sleep, waking 14 hours later refreshed and seemingly back to his former self.

The hapless DJ had been attempting to break the world record for staying awake, going 220 hours without sleep. This was the 1950s, but we know the details because his slow mental disintegration was recorded in meticulous detail by psychiatrists from Detroit’s Lafayette Clinic.

Since then, “wakeathons” have been banned in most countries and Guinness World Records no longer lists them because the long-term physical risks include cancer and heart disease and the acute mental effects are almost indistinguishable from psychosis. As the pressure to sleep builds, it’s almost as if the delusions, terrors and visions of our dream world escape into waking consciousness.

Dreams are the altered state of consciousness almost everyone experiences every night, whether we remember them or not. Sleep and dreaming are vital for maintaining physiological and emotional stability, but how exactly do they stop us from losing the plot? The answer, it seems, helps to explain the mind-healing potential of all kinds of altered state, from meditation, hypnosis and virtual reality to near death experiences and psychedelic trips.

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To understand why, it’s important to grasp how brains generate conscious experience. Rather than laboriously using incoming data from our sense organs to assemble internal representations of our surroundings from scratch, moment by moment, the brain deploys “virtual-reality” models to predict what’s happening, allowing us to stay one step ahead of the game in a noisy, confusing, fast-moving world. Only the discrepancies between the brain’s predictions and sensory data, known as “prediction errors”, are allowed to pass upwards through its information-processing hierarchies to update the models – to learn.

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Our brains have evolved to model the world in increasingly fine detail. “The brain is of itself the model,” explains Karl Friston, a neuroscientist at University College London. “So all the connectivity, all the structuring, all the delicate wiring constitutes a model of associations, a connectivity in there that’s meant to emulate in some way what’s out there.”

But this setup has a major downside, because while the models become more accurate over time, they invariably become less efficient and flexible. They lose their plasticity. The dilemma for the brain is rather like that of a multinational company that over the years has got itself tied up in red tape. Despite the energy and creativity that marked its origins as a startup, the business is now bogged down in pointless bureaucracy that not only riles customers but also makes it less innovative and responsive to changes in market conditions.

For humans, as our virtual models get increasingly complex, the more paranoid, cranky and dysfunctional we become. It turns out the role of sleep and dreaming may be to streamline these models, paring them down to their bare essentials. At the neural level, this involves “pruning” any weak, redundant synapses (the connections between nerve cells) that have sprouted during the day’s learning experiences.

Crucially, like isolating a computer from the network while overnight maintenance is carried out, this optimisation can only take place once the brain’s information-processing hierarchies have been taken offline. In REM (rapid eye movement) sleep, this is done by blocking bottom-up inputs from the senses, paralysing our muscles and stifling top-down inputs from prefrontal regions responsible for planning and rational decision-making. The brain’s virtual-reality generator creates conscious experience just as it does in waking consciousness, but now it is unconstrained by the evidence of our senses or the reality checks provided by prefrontal regions. No wonder our dreams are so weird.

This in a nutshell is the idea put forward in 2014 by Friston and his colleagues Allan Hobson of Harvard Medical School and Charles Hong of Johns Hopkins University in Baltimore. Friston believes the very same principle underlies the therapeutic promise of other altered states such as those induced by meditation and psychedelics, which also take the brain’s virtual models offline temporarily, opening a window of opportunity for relearning entrenched ways of thinking and behaving.

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While our dreams provide a nightly prune of our synapses after the day’s learning experiences, other altered states have the potential to cut through rigid, unhelpful models that may have been years or even decades in the making, for example the ruminative thought patterns that underlie anxiety and depression, and the cravings of addiction.

To stay mentally well, it seems, we may have to disconnect from reality once in a while. “But if you want to relearn,” says Friston, “if you want to explore new hypotheses about the world, you need to do this because these are the very same physiological, synaptic mechanisms necessary for neural plasticity and restructuring.”

The sharpest tools in this box are turning out to be psychedelics such as LSD and psilocybin, the active constituent of magic mushrooms. In a pilot study by Imperial College London and the Beckley Foundation, for example, after just two doses of psilocybin combined with psychotherapy, 67 per cent of patients with treatment-resistant depression were in remission a week later and 42 per cent were still free of symptoms after three months. Larger, randomised controlled trials are under way.

Other preliminary studies have found that psilocybin can significantly reduce the anxiety associated with life-threatening illnesses and help smokers to quit, and research in the 1950s and 1960s – before psychedelics were made illegal – suggested that LSD is an effective treatment for alcoholism.

Psychedelics appear to work by disrupting the inflexible models that govern our thoughts and behaviour, bringing alternatives to the fore. They do this by binding to a type of serotonin receptor found in abundance in a network of prefrontal regions known as the default mode network, high in the brain’s information-processing hierarchy.

Highly stressful events such as starvation or cardiac arrest, by triggering the release of a flood of serotonin, may trip the very same switch in the brain. This may explain the psychedelic-like visual effects, euphoria and mystical revelations characteristic of near death experiences. Remarkably, in common with the long-term effects of high doses of psychedelic observed in several studies, people who have survived a near death experience often report long-lasting improvements in psychological wellbeing and less fear of dying.

Meditation provides a rather gentler alternative for those wishing to restore plasticity to their brains. Mindfulness-based therapies have proven their worth in clinical trials for preventing relapse in depression, for example, and have shown promise in treating addiction. Rather than a chemical reboot, meditation and mindfulness dial down the activity of the default mode network by training patients to focus their attention on bodily sensations such as the breath. Over time, this has the effect of diminishing the influence of the top-down models responsible for craving and overly ruminative, self-critical thinking styles.

Another powerful altered state, hypnosis, also involves highly focused attention. When patients listen to the voice of a hypnotherapist this creates a state of absorption that temporarily suspends activity in parts of their prefrontal cortex responsible for executive control. This enhances their suggestibility, allowing the therapist to supplant the rigid cognitive models responsible for things like overeating in obesity, phobias such as fear of needles, and chronic pain.

The newest and one of the most promising therapeutic altered states is that induced through virtual reality technology. When patients don a VR headset and enter a specially designed virtual world, even though on an intellectual level they know it isn’t real, research suggests that the experience can nonetheless reshape their brain’s models. By exposing them in this safe environment to some of their worst nightmares, they can relearn unhelpful conditioning such as excessive fear of heights and paranoid delusions about strangers.

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Altered states even challenge the models that underpin our sense of selfhood, with potential benefits for wellbeing. By simulating an out-of-body experience, for example, a study suggests that VR can make people less afraid of dying, presumably through the implicit suggestion that consciousness can exist without a body. What’s more, the therapeutic effects of psychedelics in conditions such as depression, anxiety and addiction appear to be mediated by their ability to evoke the profound mystical experiences – such as feeling “at one with the universe” – that occur when the drugs dissolve people’s ego boundaries.

The long-term effects of such experiences include a renewed sense of wonder, a greater openness to new experiences and feelings of connectedness with nature and other people. While much research remains to be done, the “reboots” provided by altered states of consciousness – like the nightly reboots of dreaming – could restore our joie de vivre.

WARNING: Hallucinogenic drugs such as mushrooms containing psilocybin are a Class A drug according to UK law. Anyone caught in possession of such substances will face up to seven years in prison, an unlimited fine, or both. More information and support for those affected by substance abuse problems can be found at

Am I Dreaming? The new science of consciousness and how altered states reboot the brain by James Kingsland (£14.99, Atlantic Books) is out now.


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