Sleep and Dreaming: The Impact on Learning and Performance

Transcription

1 Sleep and Dreaming: The Impact on Learning and Performance Tracey Tokuhama-Espinosa, Ph.D. Harvard University, Psych 1609 Neuroscience of Learning and Behavior Change Week 7: October 21, 2014

2 Based on: Dreaming: An introduction to the science of sleep (2002) by J. Allan Hobson and Sleep and dreaming: Scientific advances and reconsiderations (2003), edited by E.F. Pace-Schott, M. Solms, M. Blagrove and S. Harnas

3 A Less Romantic View of Sleep (Hobson): As conscious experience, dreaming is nothing but occasional awareness of brain activation in sleep. Waking and dreaming are two states of consciousness, with differences that depend on chemistry. The Formal Features of dreaming include: Perceptual (how we perceive) Cognitive (how we think) Emotional (how we feel)

4 Sleep and Dreaming Have an Impact on the Brain s Ability to Learn The role of Memory and Attention (Stickgold & Walker, 2013)

5 Sleep Permits the Body and Mind to be Focused and Pay Attention (Hobson & Pace-Schott, 2002)

6 Sleep Permits The Body and Mind to Perform Consistently (Mitru, Millrood & Wey, 2008; Wolfson& Carskadon, 1998)

7 Memories Are Consolidated During Dreaming Memories are stored in different neural pathways depending on the mode of learning, extent of prior knowledge, or level of importance assigned by learner. Memories are consolidated during REM (Rapid Eye Movement) sleep, when most dreams occur, due to neurotransmitters present only during this stage. (Diekelmann & Born, 2010; Diekelmann, Wilhelm & Born, 2009; Stickgold, 2009; Stickgold & Walker, 2007; Wamsley, Tucker, Payne, Benavides & Stickgold, 2010).

8 Memory is Limited The brain doesn t keep a perfect record of events, but rather filters everyday occurrences and forgets a large amount of what happens.

9 The Brain is Selective v Only some things make it to longterm memory v Only memories in long-term storage can be used to learn. Figure 4. Cognitive circuits as shown at index.html. Circuits from left to right. Orange: consolidated declarative long-term memory. Green: short-term declarative memory. Purple: working memory/information processing. Blue: Behavioral memory action selection. Black: behavioral memory output. Red: cognitive control. Yellow: cortical information flow regulation. Downloaded 1 Mar 2015 from

10 Impact of Sleep and Dreaming on Learning v Sleep impacts activeworking memory. v Dreaming (REM sleep) impacts long-term memory, learning and its underlying plasticity. (Kopasz, Loessl, Hornyak, Riemann, Nissen, Piosczyk and Voderholzer, 2010)

11 What is Normal in Sleep Patterns? Short sleepers (four to six hours a day) are no more abnormal or unusual than long sleepers (eight to ten hours a day). People do not always sleep the same amount each day: Social customs Climate Personal experience (Hobson, 2002)

12 Sleeping Less Than Normal When we do sleep less than normal, we are able to compensate very well, especially if the stakes are high. If we are very motivated either by award or the need to avoid disaster we can usually manage to squeeze a little more cognitive competence out of our weary brains. (Hobson, 2002, pp )

13 Sleep Hygiene

14 However. Sleep curtailment compromises one s abilities to be attentive and to organize mental activity efficiently and effectively. To read, to write, to listen, and to tell, one needs a good night s sleep. Additionally, lack of sleep leads towards a tendency of: Intense and bizarre dreams Higher risk of infection Loss of temperature regulation of the body (Hobson, 2002, pp )

15 Paradigm Shift in Understanding the Purpose of Dreams Freud/Psychology: Content and suppressed desires Hobson/Physiology: Focus on formal features rather than on content, including emotional sensation. Because of its broad reach, dream research offers the possibility of bridging the gaps in these fields [of philosophy, psychology, literature, physiology ] (Pace-Schott et al.)

16 Primary Goals of Current Sleep Research Related to Dreaming: 1. Locate the physical areas in the brain triggered or changed by the dream state. 2. Determine what happens in the brain electrically and chemically that causes the features of dreaming. Electrically the brain remains consistently active in sleep; Chemically, parts of the brain change drastically (Hobson: 68). 3. Explain the purpose of dreaming.

17 Physical Areas of the Brain Related to Dreaming and Sleep: REM sleep (dreaming) is controlled by pontine brain stem mechanisms Dreaming is controlled by the forebrain mechanisms

18 What is the Purpose of Sleep? BODY: 1. Only mammals have thermoregulation and only mammals have REM sleep so it is likely that these two functions and dreaming are tied together in some way, (Hobson, 2002, p. 86). 2. When dreaming, acetylcholine is present, and effectively allows that brain to stop thermoregulation (and regenerate physically). BRAIN and MIND: 1. REM sleep sub-serves consolidation of memory, (Hobson, 2002, p.120; Stickgold, 2006) though this may take place only during REM sleep-windows (Carlisle Smith) and occur between several days to a week. 2. Hypothesis: Bits of declarative memory but not entire scenarios are transferred out of the hippocampus when the brain is reactivated in REM sleep. 3. Psychological release (mental regeneration).

19 Chemical Changes That Occur During Dreaming We can safely conclude that REM sleep dreaming is mediated by acetylcholine when noradrenalin and serotonin are at low levels (Hobson, 2002, p.69). Dreaming shows an association with the lack of noradrenalin and serotonin in the REM sleep-activated brain (brought on by the presence of acetylcholine). Noradrenalin and serotonin are known to be necessary for attention, learning, and memory (and by implication for orientation and active reasoning) (Hobson, 2002, p.113).

20 Chemical Areas of the Brain Related to Dreaming: Cortical areas of the parietal lobe: Increased activity Ø Hallucinations Dorsolateral prefrontal cortex: Decrease in the activation of the chemical systems (noradrenalin and serotonin) Ø Ø Ø Ø Reduces memory Confuses directed thought Decreased self-reflective awareness Decreases logical reasoning

21 All Mammals Dream REM sleep is biologically important to all mammalian life REM sleep sub-serves body temperature regulation (thermoregulation), perhaps most basic of all mammalian housekeeping functions REM sleep is organized in the brain stem ( old brain )

22 REM Sleep = Dreaming? REM can occur without dreaming and dreaming can occur without REM these two states are controlled by different brain mechanisms. REM is controlled by cholinergic brainstem mechanisms whereas dreaming seems to be controlled by dopaminergic forebrain mechanisms. However, in 70-95% of awakenings from REM state, normal subjects report they have been dreaming. Dreaming is also present in 5-10% of NREM awakenings. So while REM and Dreaming are independent, there is a strong correlation between REM sleep and Dreaming. (Solms in Sleep and Dreaming, 2003,p. 51).

23 Dreams Can Occur Throughout Sleep Sleep onset NREM REM (However, NOT in Deep Sleep)

24 REM Sleep and a New Purpose of Dreaming? Our dreams are emotional Our level of emotional competence has a high survival value We need first and foremost to know when to approach, when to mate, when to be afraid and when to run for cover We refresh these skills every night, (Hobson, 2002, p. 88).

25 REM Sleep Throughout the Lifespan: Due to chemical changes and system development in the body (Hobson, 2002, p. 78): At 26 weeks of gestation babies spend almost 24-hours a day in REM Newborns spend an average of 16-hours a day in REM sleep. One-year olds about 12-hours sleeping and 3 in REM Ten-year olds about 10-hours sleeping and 2.5 in REM Twenty-year-olds about 8- hours sleeping and 2 in REM

26 Characteristics of Sleep Humans spend approximately 25% of sleeping hours in a state of paradoxical cerebral activation, accompanied by REM (Aserinsky & Keitman 1953; 1955) This state occurs in roughly minute cycles, alternating with four well-defined stages of sleep known as non-rem (NREM) sleep.

27 Characteristics of Normal Dreams: Rich and varied internal percepts, especially sensory motor, auditory, anti-gravitational, hallucinations 1. Loss of awareness of self (self-reflective awareness) 2. Loss of orientational stability 2. Delusional acceptance of wild events as real 3. Bizarreness deriving from the discontinuity of character incongruity 4. Emotional intensity and variety 3. Loss of directed thought 4. Reduction in logical reasoning 5. Poor memory both within and after the dream.

28 Dreaming As a Mental Illness? formally speaking, dreaming and severe mental illness are not only analogous but identical (Hobson, 2002, pp ) After all, dreaming is a psychotic state Psychosis is, by definition, a mental state characterized by hallucinations and/or delusions (Hobson, 2002, p.99) Descartes/Philosophy: I am accustomed to sleep and in my dreams to imagine the same things that lunatics imagine when awake.

29 Dreams and Mental Illness The Mental Status Exam is a comprehensive checklist of mind functions that are known to be disrupted by organic brain disease and include the following categories: Consciousness: Clear or clouded? Attention: Focused or distractible? Intellectual: Sharp functions or dull? Perceptions: Externally driven or hallucinated? Cognition: Logical or illogical? Emotion: Stable or unstable/ uncontrollable? Memory: Good or poor? Abstraction: Symbolic or concrete?

30 Can Efficient or Productive Sleep be Taught? When the brain is most open to suggestions while dreaming: Sleep Onset: Particularly fruitful state for the elaboration of fantasy and dream-like mental activity Lucid dreaming REM sleep (see Hobson, pp ) Sensory-motor hallucinations in REM When the brain is dreaming it is capable of simulating acts of movement (motor acts) which are extremely convincing

31 Productive Sleep Answer the following: 1. What are the ways that dreams can be used to solve problems? 2. Who are some people you have heard of that use(d) their sleep time to resolve problems? 3. What are some characteristics of problems that can be solved while sleeping? (Concrete? Abstract? Form? Content?)

32 Thoughts on Dreams (back to the Romantic view): I don't use drugs, my dreams are frightening enough. M. C. Escher Who looks outside, dreams; who looks inside, awakes. Carl Gustav Jung Dreams are the touchstones of our character. Henry David Thoreau Whatever you can do or dream you can, begin it. Boldness has genius, power, and magic in it. Johann Wolfgang von Goethe ( )

33 References Astill, R. G., Van der Heijden, K. B., Van IJzendoorn, M. H., & Van Someren, E. J. (2012). Sleep, cognition, and behavioral problems in school-age children: A century of research meta-analyzed. Psychological Bulletin, 138(6), Brawn, T. P., Fenn, K. M., Nusbaum, H. C., & Margoliash, D. (2008). Consolidation of sensorimotor learning during sleep. Learning & Memory,15(11), Carskadon, M. A., Acebo, C., & Jenni, O. G. (2004). Regulation of adolescent sleep: implications for behavior. Annals of the New York Academy of Sciences, 1021(1), Den Wittenboer, V. (2000). Time in bed, quality of sleep and school functioning of children. Journal of Sleep Research, 9(2), Diekelmann, S., & Born, J. (2010). The memory function of sleep. Nature Reviews Neuroscience, 11(2), Diekelmann, S., Wilhelm, I., & Born, J. (2009). The whats and whens of sleepdependent memory consolidation. Sleep Medicine Reviews, 13(5), Durrant, S. J., Taylor, C., Cairney, S., & Lewis, P. A. (2011). Sleep-dependent consolidation of statistical learning. Neuropsychologia, 49(5),

34 References Hobson, J. A., & Pace-Schott, E. F. (2002). The cognitive neuroscience of sleep: neuronal systems, consciousness and learning. Nature Reviews Neuroscience, 3(9), Kopasz, M., Loessl, B., Hornyak, M., Riemann, D., Nissen, C., Piosczyk, H., & Voderholzer, U. (2010). Sleep and memory in healthy children and adolescents a critical review. Sleep Medicine Reviews, 14(3), Landsness, E. C., Crupi, D., Hulse, B. K., Peterson, M. J., Huber, R., Ansari, H.,... & Tononi, G. (2009). Sleep-dependent improvement in visuomotor learning: a causal role for slow waves. Sleep, 32(10), Margoliash, D. (2010, March). Sleep and Learning. In APS March Meeting Abstracts (Vol. 1, p. 6001). Stickgold, R. (2005). Sleep-dependent memory consolidation. Nature, 437(7063), Stickgold, R., & Walker, M. P. (2007). Sleep-dependent memory consolidation and reconsolidation. Sleep Medicine, 8(4), Stickgold, R., & Walker, M. P. (2013). Sleep-dependent memory triage: evolving generalization through selective processing. Nature neuroscience, 16(2),

35 References Walker, M. P., & Stickgold, R. (2005). It's practice, with sleep, that makes perfect: implications of sleep-dependent learning and plasticity for skill performance. Clinics in Sports Medicine, 24(2), Walker, M. P., & Stickgold, R. (2010). Overnight alchemy: sleep-dependent memory evolution. Nature Reviews Neuroscience, 11(3), Walker, M. P., Stickgold, R., Jolesz, F. A., & Yoo, S. S. (2005). The functional anatomy of sleep-dependent visual skill learning. Cerebral Cortex, 15(11), Wamsley, E. J., Tucker, M., Payne, J. D., Benavides, J. A., & Stickgold, R. (2010). Dreaming of a learning task is associated with enhanced sleep-dependent memory consolidation. Current Biology, 20(9), Wilhelm, I., Metzkow Mészàros, M., Knapp, S., & Born, J. (2012). Sleep dependent consolidation of procedural motor memories in children and adults: the pre sleep level of performance matters. Developmental Science, 15(4), Wilhelm, I., Prehn-Kristensen, A., & Born, J. (2012). Sleep-dependent memory consolidation What can be learnt from children?. Neuroscience & Biobehavioral Reviews, 36(7),

36 References Wolfson, A. R., & Carskadon, M. A. (1998). Sleep schedules and daytime functioning in adolescents. Child Development, 69(4), Wolfson, A. R., & Carskadon, M. A. (2003). Understanding adolescents sleep patterns and school performance: a critical appraisal. Sleep Medicine Reviews, 7(6),

37 Contact information: Tracey Tokuhama-Espinosa, Ph.D.