The Diary of a CEODr. Guy Leschziner: Pursuing perfect sleep worsens insomnia
Leschziner explains why chasing perfect sleep is making insomnia worse; he walks through CBT-I, light timing, and why a third of life evolved for sleep.
CHAPTERS
- 0:00 – 4:20
Extreme Sleep Behaviours and Introducing Dr Guy Leschziner
The episode opens with shocking examples of people cooking, driving, and even committing homicide while sleepwalking, leading into Dr. Guy Leschziner’s credentials and the scale of his clinical experience. The host also briefly explains a subscriber raffle before beginning the deep dive into Leschziner’s work.
- •Sleepwalking can involve complex, dangerous behaviours, including violence, with legal implications (e.g., the Kenneth Parks case).
- •Dr. Guy Leschziner is a neurologist and sleep physician running one of Europe’s largest sleep centres, with ~25,000 sleep studies and ~100,000 patients seen.
- •Sleep problems are widespread: ~30% experience insomnia annually; huge proportions with sleep apnea remain undiagnosed.
- •The show frames the conversation around solutions for insomnia and poor sleep.
- 4:20 – 15:00
Why Study Sleep? Neurology, Extremes of Experience, and Sleep Medicine
Leschziner explains his fascination with people at the extremes of human experience and how neurology and sleep medicine intersect. He sketches his background, defines neurology and sleep medicine, and describes his sleep disorders centre and patient volume.
- •Neurology is the clinical study of the brain and nervous system in disease (epilepsy, Parkinson’s, nerve disorders, certain sleep disorders).
- •Sleep medicine has exploded over the last 20–30 years as links to physical and mental health became clearer.
- •His sleep centre at Guy’s & St Thomas’ has 10 in‑patient beds, ~15 consultants, ~50 staff, 2,500 sleep studies annually, and ~10,000 patients/year.
- •Sleep and the brain intersect at every level: “sleep is of the brain, by the brain, and for the brain.”
- 15:00 – 24:40
Is Sleep Really That Important? Evolution, Systems, and Public Attitudes
The discussion turns to why sleep is evolutionarily conserved and crucial for survival, citing unihemispheric sleep in dolphins and the universality of circadian rhythms. Leschziner contrasts past cultural bravado about short sleep with today’s growing, sometimes excessive, focus on sleep.
- •Sleep entails vulnerability; the fact evolution retained it suggests huge adaptive value.
- •Circadian rhythms appear in virtually all life forms, implying ancient biological priority.
- •Sleep affects immune function, blood pressure, cardiovascular risk, diabetes, pain perception, depression, and anxiety.
- •Public awareness has improved but is uneven: many still underestimate sleep, while some now over‑obsess and inadvertently fuel insomnia.
- 24:40 – 36:40
The State of Our Sleep: Insomnia, Sleep Apnea, Restless Legs, Sleepwalking
Leschziner lays out prevalence data for major sleep disorders and clarifies differences between sleep deprivation and insomnia. He highlights obstructive sleep apnea and restless legs as underdiagnosed but common problems and notes that most patients can be substantially helped, if not always cured.
- •Around 20% of adults are chronically sleep‑deprived due to lifestyle and prioritisation.
- •About 30% experience insomnia annually; roughly 10% have chronic insomnia (>3 months).
- •Obstructive sleep apnea likely affects ~10–12% of adult men and ~6% of women; ~80% in the UK are undiagnosed.
- •Restless legs syndrome affects ~5% of adults; sleepwalking 1–2%.
- •Most sleep disorders are treatable or manageable, even if not curable.
- 36:40 – 51:40
Modern Life, Tribes, and What Healthy Sleep Really Looks Like
The conversation contrasts sleep in pre‑industrial societies with modern insomnia, discussing seasonal variation, mid‑night awakenings, and possible segmented sleep in history. Leschziner then explains individual variation in sleep need, the population‑level sweet spot (7–8.5 hours), and the puzzling risks associated with long sleep.
- •In some traditional societies insomnia is rare; some languages lack a word for it, suggesting modern culture fosters insomnia.
- •Normal sleep includes brief awakenings; up to ~30 minutes awake per night is not pathological.
- •Mediterranean siesta patterns and other variants can be entirely normal.
- •Genetics influences both sleep duration and timing; rare families function well on ~4 hours/night.
- •Population data show higher mortality with <7 hours and >8.5 hours, though long sleep may be a marker of underlying illness or prodromal neurodegeneration.
- 51:40 – 1:03:20
Sleep Deprivation, Weight, Metabolism, and Emotional Fallout
Leschziner details how short or disrupted sleep promotes weight gain and metabolic problems via appetite hormones, cravings, and insulin resistance. The host adds personal observations about sugar cravings when tired, and they discuss how sleep deprivation affects reward systems, mood, and emotional control.
- •Even one night of sleep loss can markedly increase calorie intake next day.
- •Long‑term data (e.g., 18‑year nurse study) link <6 hours’ sleep to higher baseline weight and faster weight gain.
- •Treating sleep apnea can enable previously unsuccessful weight loss in some obese patients.
- •Sleep loss impairs glucose tolerance and increases insulin resistance, relevant for diabetes risk.
- •Sleep‑deprived people often crave sugary, high‑energy foods and exhibit greater emotional reactivity and irritability.
- 1:03:20 – 1:18:20
Circadian Rhythms, Melatonin, and the Role of Light
The episode dives into circadian biology: cellular clocks, the suprachiasmatic nucleus, melatonin, and how light (especially blue) adjusts our internal timing. They explore how genetics, age, and environment shape chronotype, and how modern lighting and screens delay sleep and create social jetlag.
- •Every cell has a 24‑hour rhythm; ~40% of cellular genes oscillate circadianly in vitro.
- •The suprachiasmatic nucleus (SCN) in the hypothalamus coordinates body clocks; melatonin secretion is a chemical marker of circadian phase.
- •Light, especially blue wavelengths detected by retinal ganglion cells, is the dominant zeitgeber; signals run directly from the eye to the SCN.
- •Melatonin tablets can shift circadian phase but create a feedback loop with endogenous melatonin.
- •Blind individuals who lose light input often develop “non‑24‑hour” sleep‑wake cycles (e.g., 25‑hour days cycling around the clock).
- •Genetics explains up to ~50% of chronotype; teenagers tend to shift later, older adults earlier.
- 1:18:20 – 1:26:40
Screens, Blue Light, Partners, and the Real Meaning of Sleep Hygiene
The host asks about watching thrillers in bed and using phones late at night, prompting a nuanced discussion of sleep hygiene as highly individual. Leschziner explains how activities in bed train the brain’s associations, why dark quiet rooms matter, and how partners, alcohol, large meals, and environment can help or hinder sleep.
- •Device blue light alone is usually too weak to cause acute insomnia, but chronic late‑night use delays circadian phase and encourages later bedtimes.
- •Engaging, arousing content (social media, intense shows) keeps the brain wired and delays sleep onset.
- •Good sleepers can sometimes break “rules” without issue; highly sleep‑reactive people are more vulnerable to environmental disruption.
- •Poor sleep hygiene includes working in bed, constant screens in the bedroom, heavy evening caffeine and alcohol, and no wind‑down time.
- •Darkness at night is important; evening light exposure in sleep may impair sleep quality and is tentatively linked to diabetes risk.
- •Sharing a bed can help or harm depending on noise, movement, snoring, and individual sleep reactivity.
- 1:26:40 – 1:48:20
Assessing Insomnia, Misperception of Sleep, and the Limits of Trackers
Leschziner outlines how he evaluates an insomniac: differentiating insomnia from other sleep disorders and from chronic short sleep, and recognizing that people often vastly underestimate how much they actually sleep. The pair then debate sleep trackers—their research value, their motivational role, and their potential to worsen anxiety in already troubled sleepers.
- •Many patients who report “no sleep” objectively sleep 7–8 hours but with fragmentation from apnea or periodic limb movements.
- •History taking looks at triggers (life events, medications), prior sleep reactivity, and comorbid health or mental health conditions.
- •Most insomniacs are poor judges of their own sleep duration and quality; awareness circuits may remain more active at night.
- •Trackers are useful in large‑scale research and for people simply burning the candle at both ends who can choose to extend time in bed.
- •For anxious insomniacs, trackers often heighten worry, provide partly inaccurate staging data, and offer no actionable “extra sleep” solution that night.
- •Leschziner advises many insomnia patients to stop tracking and seek professional assessment instead.
- 1:48:20 – 2:05:50
The Glymphatic System, Alzheimer’s Links, and Sleep Pills vs. Melatonin
They explore the brain’s glymphatic drainage system and its proposed role in clearing beta‑amyloid during deep sleep, and why the sleep–Alzheimer’s link remains unresolved. Leschziner then discusses his cautious stance toward sleeping tablets and melatonin, favouring non‑drug treatments first and warning about psychological dependence.
- •The glymphatic system is a brain‑specific fluid drainage network analogous to the body’s lymphatic system, thought to expand in deep sleep.
- •Early studies suggested ~60% expansion during deep sleep, promoting clearance of beta‑amyloid; newer data question the exact magnitude.
- •Chronic insomnia and sleep deprivation correlate with cognitive decline and dementia, but causality vs. early disease effects is unclear.
- •Some studies link chronic sleeping pill use to dementia, but again confounding by underlying illness is likely.
- •Leschziner generally avoids prescribing hypnotics as first‑line therapy, reserving them for severe, refractory cases after non‑drug methods fail.
- •Melatonin is relatively safe but not side‑effect‑free; people can become psychologically reliant on having a pill ‘just in case’.
- 2:05:50 – 2:20:00
CBT‑I, Sleep Restriction, and Extreme Sleep Retraining
The core of insomnia treatment is unpacked: how CBT‑I tackles both the conscious worry about sleep and the unconscious conditioning that wires bed to wakefulness. Leschziner explains sleep restriction and describes an intense Australian lab protocol that uses controlled sleep deprivation and repeated brief naps to ‘reboot’ sleep associations.
- •Chronic insomnia involves both heightened arousal (conscious worry, frustration, future‑oriented fear) and maladaptive conditioning (bed = awake).
- •CBT‑I includes relaxation techniques, stimulus control, and sleep restriction to rebuild the association of bed with rapid sleep onset.
- •Sleep restriction temporarily limits time in bed to approximate actual sleep time, making people sufficiently sleepy that they fall asleep faster and stay asleep longer within that window.
- •Intensive Sleep Retraining (ISR) keeps insomniacs awake overnight, then gives 50 brief nap opportunities over 25 hours, waking them after 3 minutes of sleep each time.
- •ISR is highly effective for some but is described as a form of ‘torture’ and is not practical for most patients outside research.
- •Leschziner stresses that many people’s “sleep identity” (“I’m a bad sleeper”) becomes self‑reinforcing and is influenced by trackers and cultural narratives.
- 2:20:00 – 2:38:20
Narcolepsy, Restless Legs, Magnesium, and What Happens in the Sleep‑Deprived Brain
They briefly cover narcolepsy’s hallmark symptoms and treatment, then return to restless legs syndrome and possible benefits of magnesium. Leschziner describes how the sleep‑deprived brain redistributes sleep architecture and how local “micro‑sleeps” in cortical regions impair cognition and behaviour.
- •Narcolepsy is an autoimmune brain disorder causing excessive daytime sleepiness, vivid dreams, hallucinations, sleep paralysis, and cataplexy; it’s lifelong but treatable.
- •Restless legs syndrome creates an irresistible urge to move the legs at night, often with unpleasant sensations, disturbing both sleep onset and maintenance.
- •Magnesium appears to help some restless legs patients anecdotally, though mechanisms aren’t fully understood.
- •After sleep deprivation, the brain prioritizes deep slow‑wave sleep over REM, visible in lab recordings.
- •Even when awake, the cortex shows local episodes of electrical silence; with more sleep loss these micro‑sleeps lengthen and spread, degrading attention and cognition.
- •Mood and anxiety are tightly coupled to sleep; treating one without the other is often ineffective.
- 2:38:20 – 2:53:20
Why We Dream, Nightmares, and Emotional Processing During Sleep
The host presses Leschziner on why we dream and why nightmares exist, leading to a tour of theories about REM sleep’s functions in memory and emotional regulation. They discuss dream recall, recurrent trauma nightmares in PTSD, and the idea that dreaming might help decouple memories from overwhelming emotional charge.
- •We don’t yet know definitively why we dream; theories include memory consolidation, emotional regulation, and development of consciousness.
- •REM‑associated dreams tend to have narrative structure, but dreaming also occurs in non‑REM sleep (e.g., sleepwalking, night terrors).
- •Infants and fetuses spend large proportions of time in REM sleep, potentially supporting early brain development.
- •We rarely remember dreams unless we wake directly out of REM, leaving the dream trace partially intact.
- •In PTSD, highly emotional dreams often cause awakenings, preventing completion of emotional processing and reinforcing trauma.
- •From an evolutionary view, strong emotional memories (e.g., predator attacks) help learning, but re‑experiencing them with reduced emotional intensity would be adaptive.
- 2:53:20 – 3:06:40
Violent Parasomnias, Sleepwalking Crime, and the Kenneth Parks Case
Leschziner recounts cases where people commit serious crimes – including homicide and sexual assault – while apparently asleep, and explains how such cases are evaluated medically and legally. The dramatic Kenneth Parks case, in which a man drove 23km in his sleep and killed his mother‑in‑law, illustrates the troubling intersection of sleep disorders and accountability.
- •Complex parasomnias can involve driving, cooking, and even violent acts while parts of the brain remain in deep sleep and others are awake.
- •Frontal lobes (rational judgment) and hippocampus (memory) often remain “asleep” while motor, visual, and emotional systems are active.
- •Courts weigh prior history, evidence of similar behaviours clearly originating from sleep, and signs of planning or cover‑up when judging such cases.
- •Kenneth Parks’ acquittal hinged on accepting that the killing occurred during sleepwalking, despite financial motives and elaborate behaviour.
- •Leschziner has personally managed patients who drove cars and motorbikes in their sleep without any recollection.
- 3:06:40 – 3:18:20
Rare Sleep Disorders and the Devastating Impact on Lives
Beyond common problems like insomnia and apnea, Leschziner describes rare but dramatic conditions such as Kleine–Levin syndrome, where patients sleep almost continuously for days or weeks and behave bizarrely when awake. These cases show how sleep disorders can derail education, work, and relationships.
- •Kleine–Levin syndrome affects mostly adolescents; during episodes, they may sleep 23–24 hours/day and show confusion, hyperphagia, and disinhibited sexual behaviour.
- •Patients may appear normal between episodes but face severe disruption to schooling, work, and social life.
- •Such disorders underscore that sleep problems can be profoundly disabling and are not just about feeling a bit tired.
- •Management focuses on education, support, and symptom control rather than cure.
- 3:18:20 – 3:36:40
Synesthesia, Senses, and How the Brain Constructs Reality
The focus shifts to Leschziner’s book “The Man Who Tasted Words” and the phenomenon of synesthesia, where senses blend (e.g., words have tastes, music has colours). He uses these cases, along with hallucinations from sensory loss, to argue that perception and truth are brain‑made constructions shaped by genes and experience.
- •Synesthesia (e.g., tasting words, seeing colours with music) occurs in up to about 4% of people and is more common in autistic individuals.
- •One man’s entire reading and map of London Underground stations is overlaid with consistent tastes that have remained fixed since childhood.
- •Another musician experiences colours and even tactile sensations when hearing music.
- •Hallucinations in vision or hearing (e.g., after sensory loss or in Bill Oddie’s musical hallucinations) often arise because the brain, starved of input, generates its own stimuli.
- •These phenomena show that individual realities differ; the brain uses predictive models shaped by genes and history, so there is no simple, shared ‘truth’ of experience.
- 3:36:40 – 3:50:00
Free Will, the Seven Deadly Sins, and Brain‑Driven Behaviour
Drawing from his forthcoming book, Leschziner reflects on cases where brain pathology or drugs radically altered behaviour—aggression, gluttony, sexuality—paralleling the traditional seven deadly sins. This raises unsettling questions about moral responsibility and how much of our behaviour is truly chosen versus biologically compelled.
- •Certain anti‑epileptic drugs can cause dramatic surges in irritability and aggression in a minority of patients, which resolve when the drug is stopped.
- •Autoimmune brain inflammation, strokes, tumours, and neurodegenerative diseases can all precipitate radical personality and behavioural shifts.
- •These observations suggest that traits like wrath, greed, lust, and pride can have specific biological underpinnings.
- •If behaviour changes when brain chemistry or structure changes, the concept of free will and moral blame becomes less clear‑cut.
- •Leschziner’s third book uses the seven deadly sins as a lens on the biology of being human.
- 3:50:00 – 4:08:20
Living Without Pain, Losing Smell, and the Emotional Cost of Sensory Loss
Leschziner recounts patients with congenital insensitivity to pain and others who lose vision, smell, or hearing, revealing how much we rely on these senses for safety, memory, and mood. The host and guest reflect on how such cases reshape our view of pain, suffering, and the brain’s need for input.
- •A man and his siblings who cannot feel pain from birth repeatedly injure themselves, burn their skin for fun, and break bones without deterrent, demonstrating pain’s protective role.
- •A blind woman with persistent visual hallucinations chooses not to treat them because seeing “something” is preferable to total darkness.
- •Loss of smell, common in COVID‑19, is closely associated with depression and erodes powerful smell‑evoked memories and emotional colouring of experience.
- •Hearing loss can drive musical hallucinations and is linked to cognitive decline; preserving sensory input is important for brain health.
- •These stories show that sensations we think we’d like to avoid (like pain) are essential to normal development and identity.
- 4:08:20
Personal Impact, Burnout, and Closing Reflections
In closing, Leschziner reflects on how seeing extreme neurological and sleep conditions has broadened his understanding of medicine’s impact on patients and their families, even as NHS pressures leave clinicians burned out. The host strongly recommends his books on sleep, senses, and the biology of behaviour.
- •Writing books forced Leschziner to see beyond discrete clinical problems to the broader life consequences for patients.
- •He acknowledges NHS clinicians are widely burnt out and he himself doesn’t always care for his own wellbeing optimally.
- •He admits his own sleep is “sometimes” good, underscoring that even sleep experts aren’t perfect sleepers.
- •A listener question prompts him to reflect on difficult decisions like entering medicine, which has shaped his entire life trajectory.
- •The episode ends by highlighting his three books and the ongoing public fascination with sleep and the brain.
