Presentation on theme: "Professor Glenn Wilson, Gresham College, London SLEEP AND DREAMS."— Presentation transcript:
Professor Glenn Wilson, Gresham College, London SLEEP AND DREAMS
STAGES OF SLEEP Sleep has stages of increasing depth (difficulty in waking). Deepest sleep (Stage 4) occurs after about 1hr. Rapid eye movement (REM) sleep occurs in bursts that get longer towards morning. This is when most dreams occur.
REM SLEEP IN CATS REM sleep occurs in most mammals, especially predators like cats. Probably dreaming (rehearsing hunting skills?). REM associated with muscle relaxation. Suggested that prey animals cannot afford much sleep. “The lion and the lamb shall lie down together but the lamb won’t get much sleep” (Woody Allen, Love and Death).
SLEEP DEPRIVATION As school science project (1965) Randy Gardner stayed awake for 11 nights. Became progressively disorientated & impaired (blurred vision, slurred speech, moodiness, paranoia/delusions). When finally allowed to sleep, he slept 15hrs first night,10 on next two (i.e., he lost 90hrs but made up only 11). Proportion of Stage 4 (68%) and REM (53%) increased radically. Suffered no obvious long-term harm but rats deprived of sleep die within a few weeks.
MEMORY STORAGE Sleep important for neurodevelopment, tissue repair, immune function & memory consolidation. Material of future use is selectively stored (Van Dongen et al, 2012) Sleep spindles (rapid EEG oscillations in Stage 2) go with relocation of memories from hippocampus (short- term storage) to prefrontal cortex (“hard-drive”) thus refreshing memory capacity (Mander et al, 2011).
CIRCADIAN RHYTHM Sleep cycle controlled by oscillators in suprachiasmic nuclei of hypothalamus (handy to light input). Via a spinal detour, this modulates secretion of melatonin from pineal gland (more in darkness) which enters bloodstream. A second “clock” in the pons is responsible for REM-sleep. Jet lag, shift work, artificial light interfere with diurnal cycle. Northerly migration may also have impact. Some think our ancestors had two sleep phases in night separated by hour or so of activity (esp. in winter?).
SLEEPING PILLS Approx. 12 million hypnotics per yr prescribed in UK. Most are addictable (including barbiturates, benzodiazepines, z-drugs and melatonin). Interfere with restful sleep (deep sleep/REMs), hence fatigue & memory impairment. Linked to cancer, Alzheimer’s and higher mortality. Minimal gains in sleep (15 mins faster, 37mins. longer); half of it placebo (Huedo- Medina, 2012).
COMBATTING INSOMNIA Use bedroom only for sleeping & sex (no eating, drinking, working). Remove TV and computers (screens emit light). Ensure it is cool, quiet & dark. Regular sleep/wake times. Exercise in daytime (not late). Avoid alcohol & stimulants like caffeine before bed. Don’t lie in bed fretting - better to get up and do something. 8 hours not required by all (may be less for older people). If anxious or depressed, address the problem (self-help or CBT).
SLEEP APNOEA Interrupted breathing during sleep. May be central (brain-based) or obstructive (associated with snoring). Sleeper not aware but distressing to partner. Leads to fatigue, daytime sleepiness, moodiness, accident proneness, immune depression. Treatment may include avoidance of alcohol & sleeping pills, weight loss, oral devices that maintain open airways and surgery. Singing & playing musical instruments (e.g., didgeridoo) may help strengthen throat muscles.
NARCOLEPSY Drowsiness/sudden sleep attacks occurring at any time (often inconveniently). Associated with cataplexy – sudden muscular weakness brought on by strong emotion. Apparently intrusion of REM sleep into daytime (includes paralysis & dreams). Heritable component but occasionally linked with head injury/neurological damage. Treated by various drugs (including stimulants and SSRIs). Controlled daytime naps may help.
IN YOUR DREAMS Dreams are highly visual (usually in colour). Also emotional (esp. anxiety & abandonment but also joy). Often refer to events from previous day or week. Background stimuli incorporated (e.g., doorbell, music, water spray). Surrealistic & morphing (laws of physics don’t apply). Symbolic and metaphorical. Little sense of agency or volition (things happen to us).
LUCID DREAMS Dreamer aware they are dreaming but allow it to continue (c.f., psychotic hallucinations; believed to be real). Lucid dreamers may have control over the direction of the narrative. Some people able to learn this capacity and harness it for creativity or treatment of distressing nightmares.
DREAMS OF DISABLED PEOPLE Often dream as though they don’t have the disability. Paraplegics walk, deaf- mutes talk and sing normally (Voss et al, 2011). Genetic programming or action of mirror neurons (copying by observation)? People blind <5ys dream without visual imagery (and little REM). Colour-blind dream in colours they see. Older people more likely to dream in black & white (like media of their era).
NOCTURNAL INSPIRATION Because associations are loose, dreams may promote creative problem-solving. Examples: 1. Benzene ring inspired by dream of a snake biting its tail (Kekule). 2. Machine sewing needle (with hole near tip) came from Elias Howe’s dream of cannibals dancing with notches toward end of spears. 3. Plot of Dr Jekyll & Mr Hyde (R.L. Stevenson). 4. Frankenstein (Mary Shelley’s dream of bringing her dead baby back to life). 5. Song Yesterday (McCartney:“came in a dream”).
SYMBOLISM Freud (1900): dreams reveal unconscious desires (mostly sexual) Symbolism disguises the true meaning from the dreamer. Eysenck (1957) : function of symbolism is adjectival (adding precision & colour). You may dream of your mother as a cow or a queen, depending on whether nutritive or authoritative aspect is emphasised. Greeks had reverse theory of symbolism. Dream of sleeping with your mother means your Mother country is about to bestow an exceptional honour on you.
ACTIVATION-SYNTHESIS THEORY Hobson & McCarley (1977): REM- sleep occurs when pons becomes active, causing REMs, cortical activity and muscular paralysis. Dreams are forebrain’s attempt to make sense of random sensations (c.f. Rorschach responses). If amygdala activated, fear may be attached to a recent accident. Critics say dreams are not random but follow continuous storylines. Lesions to brainstem do not prevent them, though damage to parietal lobes may do (Solms, 2000).
CYBERNETIC THEORY Newman & Evans (1965): dreams are the experiential by-product of the “off-line” brain sorting daytime experiences, discarding the junk and placing material of future importance into suitable files where they can be accessed when required. This would account for the difficulty in remembering dreams – they are themselves memory consolidation processes.
CONTINUITY THEORY Many parallels between waking thought and dreaming. Bizarre nature of dreams has been exaggerated; most reflect waking concerns about the past, present and future (c.f., Gilbert’s Nightmare Song). Less than 10% are improbable by waking standards and while 70% are emotional - usually no more than appropriate to the dream situation. Domhoff (2011): dreams arise from a neural subsystem in the limbic, paralimbic & associational forebrain active in mind-wandering & daydreaming. Called the waking default network. Lesions to this have similar effect on waking thought & dreams.
THREAT SIMULATION Nightmares may indicate anxiety when they repeat waking life trauma. Not so much the frequency of nightmares as degree of distress caused by them that relates to psychopathology. Threat simulation theory: nightmares have evolutionary value, providing rehearsal for coping with real-life danger (virtual reality try-outs, like horror movies). 80% of dreams include threatening narratives (Valli & Revonsuo, 2009).
DREAMS AFTER 9/11 Hartmann (2008) found no increase in content involving aeroplanes or tall buildings, and no “exact replay” dreams following 9/11. However, the central images of dreams that did occur were emotionally more intense following the terrorist attacks than previously. Dreams reflect emotional charge even though agenda remains personal.
NOCTURNAL TUMESCENCE Erections in men and clitoral arousal in women occur in connection with REM sleep. Not due to sexual dreams but direct result of the brain state. May increase likelihood of sexual content & “wet dreams” (but still only 8% of dreams are sexual). Nocturnal erections are diagnostic of psychogenic erectile dysfunction in men. (Tested with a “snap gauge”).
EFFECTS OF PORNOGRAPHY The content of erotic dreams mirrors daytime sexual interests. We dream about same things we think about, fantasise, and do (i.e., dreams show continuity). Porn consumption is linked to female domination scenarios in dreams, esp. those involving celebrities and female authority figures (police officers, teachers etc.). Sexual release, whether or not using pornography, goes with fewer wet dreams (Yu, 2012).
PARASOMNIA Somnambulism (sleepwalking) occurs in 4% of people; usually results in little harm. Sexsomnia (sleep sex) also rare (often loveless & aggressive). Others grind their teeth, yell out, raid fridge, or assault a partner in their sleep. Mostly in deep sleep, but sometimes REM or fringes of waking. Eyes usually open but staring. No awareness or recall. Associated with extreme tiredness, alcohol, stress, apnoea and family history.
SLEEP RAPE & MURDER Sexsomnia has been used as a defence against rape. Tricky to substantiate but 12/18 acquittals in UK cases (14 involved alcohol). Retired Welsh steelworker Brian Thomas (59) acquitted of murder after strangling his wife Christine while asleep. Attack occurred at 3am, during a nightmare in which “he was defending their caravan against a boy racer who was attacking him”. Judge called him “a decent man and devoted husband” and the court accepted that he was not in control of his behaviour..
SLEEP-DRIVING Becky Mason (28) drove 5 miles to work in pyjamas on a Sat. night and crashed her car after being turned away by a security man (she wasn’t due in till Mon. morning). Was 3x alcohol limit but was cleared of drink-driving by a Liverpool court on expert opinion that she was asleep until the crash occurred, hence “not responsible. Defence was based on security guard’s testimony and a family history of parasomnia.
SLEEP PARALYSIS Common nightmare is an evil presence (ghost or incubus) in the bedroom that presses down upon our body. Another is being unable to run away from something in pursuit. May be related to fact that limbs are effectively paralysed during REM sleep. Occurs at fringes of waking and REM-sleep; seems very real. More likely when sleep disrupted by stress, shift work, alcohol, etc. May account for some reports of rape, parental abuse, astral projection and alien abduction.