Intro psychology sleep rhythms psychology

inro neuroscience psychology sleep

1. The Rhythms of Sleep

2. Exam 2

3. Exam 2

4. The Rhythms of Sleep

5. How and Why we Sleep What do we know about sleep? Daily rhythms and our internal clock Sleep stages & cycles Neural control of sleep Why do we sleep? How and why is sleep disturbed?

6. How and Why we Sleep What do we know about sleep? Daily rhythms and our internal clock Sleep stages & cycles Neural control of sleep Why do we sleep? How and why is sleep disturbed?

7. What do we Know About Sleep? We know HOW we sleep… Neural rhythms Hormones and neurotransmitters Biological clock But we don’t know WHY we sleep Restoration and recovery? Memory consolidation?

8. Copyright © 2009 Allyn & Bacon Amount of sleep varies among animal species Giant Sloth = 20 hours!!

9. Sleep-Deprivation Studies with Rats When the EEG indicates sleep, the floor rotates – the sleeping rat falls into the water and wakes up Yoked controls – subjected to the same floor rotations Experimental rats typically die after several days Postmortem studies reveal lesions indicative of extreme stress Carousel apparatus used for sleep deprivation

10. Studies of Sleep Deprivation in Humans 3-4 hours of deprivation in one night Increased sleepiness Disturbances of mood Poor performance on tests of vigilance 2-3 days of continuous deprivation Experience microsleeps, naps of 2-3 seconds. Longer periods of deprivation No effects on motor performance No effects of cognitive performance (IQ) May affect creativity Correlated with dementia

11. Human Sleep Deprivation: 1 st World Record Holder, Randy Gardner

12. How and Why we Sleep What do we know about sleep? Daily rhythms and our internal clock Sleep stages & cycles Neural control of sleep Why do we sleep? How and why is sleep disturbed?

13. Sleep & Circadian Rhythms

14. Biological Rhythms Circadian rhythm: Any biological process that displays endogenous, entrainable oscillation of ~24 hours Often controlled by light or other internal clocks However it is also endogenously generated , coming from programmed mechanisms in our brain, persisting even in the absence of external cues Other rhythms include ultradian and infradian

15. Q

16. Timing Mechanisms Zeitgebers- Environmental cues that entrain circadian cycles (light-dark, tides) Without zeitgebers , animals display “ Free-Running Rhythms ” Humans ~25 hrs

17. The Retino - hypothalamic tract connects the retina with the SCN The circadian clock is located in the Suprachiasmatic Nucleus Even when isolated, it shows cycles of electrical, metabolic and biochemical activity Photoreceptors that entrain the SCN are light-sensitive ganglion cells !!

18. Suprachiasmatic Nucleus (SCN) Light info is sent directly to the SCN (in the hypothalamus)

19. SCN: Primary biological clock, receiving projections from retinohypothalamic pathway

20. Our OTHER Photoreceptors

21. Our OTHER Photoreceptors

22. Suprachiasmatic Nucleus (SCN)

23. SCN signaling of Pineal Gland SCN signals the pineal gland about light/dark phases Pineal gland secretes melatonin during dark phases Lesions of the SCN or pineal gland disrupt rhythms controlled by light/dark phases Become arrhythmic Abolish annual breeding cycles

24. The Rhythms of Sleep Pt2

25. Melatonin Levels Throughout the Day

26. Function of Melatonin Synthesized from serotonin in the pineal gland Melatonin is not a sleep aid, but may be used to shift circadian rhythms (e.g. for jet lag) Melatonin levels follow circadian rhythms controlled by the Suprachiasmatic Nucleus Pineal gland triggers seasonal reproductive changes in fish, birds, reptiles, and amphibians – human function is unclear

27. How and Why we Sleep What do we know about sleep? Daily rhythms and our internal clock Sleep stages & cycles Neural control of sleep Why do we sleep? How and why is sleep disturbed?

28. Sleep Cycles 4 Stages Stage 1 Stage 2 Stage 3 REM Stages differ by: Neural Activity Eye Movement Muscle Activity Non-REM Sleep Slow-wave Sleep

29. Stages of Sleep and How They’re Studied Electro-oculogram (EOG) monitors eye movement Electromyogram (EMG) Measures muscle activity Electroencephalogram (EEG) Measures brain waves

30. EEG Activity

31. Wakefulness Beta : Irregular, low amplitude, typical of alertness and active thinking Alpha : Regular, medium frequency, typical of resting

32. When Sleep begins… Stage 1 : Alpha to theta waves with vertex spikes; transition from wakefulness to sleep Stage 2 : Theta waves continue, but now marked by sleep spindles and K-complexes

33. Slow Wave Activity Stage 3 : Beginning of deep or slow wave sleep and involves a combination of theta and delta The deep, restful sleep, where it’s hard to wake you up High amplitude, low frequency

34. Sleep Stages Through the Night

35. PGO Waves REM sleep is also associated with distinctive pattern of high amplitude electrical potentials known as PGO waves Waves neural activity begin in the pons, followed by lateral geniculate nucleus of the thalamus, and then in the occipital cortex REM deprivation results in high density of PGO waves when allowed to sleep normally

36. The Rhythms of Sleep Pt. 3

37. REM Sleep and Dreaming 80% of awakenings from REM lead to dream recall External stimuli can be incorporated into dreams Dreams run on “ real time ” Virtually everyone dreams Sleepwalking (somnambulism), sleeptalking and bedwetting (enuresis) occur more frequently during SWS than during REM sleep, when core muscles are relaxed

38. Lucid Dreaming Dreams in which the sleeper realizes they are in a dream Can be trained through intention setting before bed, as well as use of different electronic devices Studies of this experience has allowed the understanding of the experience of time in dreams

39. Book Club! Want to learn more about sleep?

40. Sleep Pt.3

41. How and Why we Sleep What do we know about sleep? Daily rhythms and our internal clock Sleep stages & cycles Neural control of sleep Why do we sleep? How and why is sleep disturbed?

42. Human Sleep Patterns Change with Age

43. The Typical Pattern of Sleep in an Elderly Person

44. REM Sleep in Humans and Other Mammals REM sleep evolved in some vertebrates: Nearly all mammals display both REM and SWS Birds display both REM and SWS Dolphins do not show REM sleep, perhaps because relaxed muscles are incompatible with the need to surface to breathe In dolphins and birds, only one hemisphere enters SWS at a time—the other remains awake

45. Sleep in Marine Mammals

46. Sleep is an Active State Mediated by At Least Four Interacting Neural Systems A forebrain system —generates SWS A brainstem system —activates the forebrain to wakefulness A pontine system —triggers REM sleep A hypothalamic system —coordinates the other three

47. Brain Mechanisms Underlying Sleep

48. How and Why we Sleep What do we know about sleep? Daily rhythms and our internal clock Sleep stages & cycles Neural control of sleep Why do we sleep? How and why is sleep disturbed?

49. Differing Sleeping Patterns

50. Why do we Sleep? Sleep for Energy Conservation The smaller the mammals, the higher the metabolic rate, the more time needed for sleep Niche Adaptation Forces conformity to ecological niche of day/night Restoration and Recovery Sleep helps to restore and repair brain tissue Memory Consolidation Sleep restores and rebuilds our fading memories

51. Copyright © 2009 Allyn & Bacon Amount of sleep varies among animal species Giant Sloth = 20 hours!!

52. Why do we Sleep? Sleep for Energy Conservation The smaller the mammals, the higher the metabolic rate, the more time needed for sleep Niche Adaptation Forces conformity to ecological niche of day/night Restoration and Recovery Sleep helps to restore and repair brain tissue Memory Consolidation Sleep restores and rebuilds our fading memories

53. Brainwashing! (The good kind) Recovery: Sleep Cleans our Brains! http://www.npr.org/blogs/health/2013/10/18/236211811/brains-sweepthemselves-clean-of-toxins-during-sleep Sleep drives metabolic clearance in adult brains ( Science, October 2013)

54. Brain Cleaning Editor’s Summary: Taking out the Trash The purpose of sleep remains mysterious. Using state-of-the-art in vivo two-photon imaging to directly compare two arousal states in the same mouse, Xie et al. found that metabolic waste products of neural activity were cleared out of the sleeping brain at a faster rate than during the awake state. This finding suggests a mechanistic explanation for how sleep serves a restorative function, in addition to its well-described effects on memory consolidation. Science, 342, 373-377. October 2013

55. More Space Between Cells During Sleep!

56. Conclusion of paper: The Purpose of sleep has been the subject of numerous theories since the time of the ancient Greek philosophers. An extension of the findings reported here is that the restorative function of sleep may be due to the switching of the brain into a functional state that facilitates the clearance of degradation products of neural activity that accumulate during wakefulness.”

57. Why do we Sleep? Sleep for Energy Conservation The smaller the mammals, the higher the metabolic rate, the more time needed for sleep Niche Adaptation Forces conformity to ecological niche of day/night Restoration and Recovery Sleep helps to restore and repair brain tissue Memory Consolidation Sleep restores and rebuilds our fading memories

58. Sleep (Dreams?) and Memory

59. Patterns of Activity During Encoding and Consolidation

60. Dreaming to Forget REM sleep erases spurious associations between neurons before they can inappropriately trigger synaptic plasticity and learning Reverse Hebbian Rule: Weakens connections when a dream co-activates neighboring neurons Weak associations are actively down-regulated by random input

61. Sleep and Insight Not just for consolidation and cleaning up, but also for restructuring of experience

62. Dreaming and Insights

63. Dreams and Meaning Freud: Provide insight to subconscious Dreams constitute a disguised attempt at wish fulfillment Criticized because it cannot be proven wrong Activation-Synthesis Model: Dreams may have no meaning at all Represent random activity from the brainstem that is sent to cortex Cortex “synthesizes” an explanation, weaving a story from random inputs

64. How and Why we Sleep What do we know about sleep? Daily rhythms and our internal clock Sleep stages & cycles Neural control of sleep Why do we sleep? How and why is sleep disturbed?

65. Sleep Disorders Sleep paralysis —brief inability to move just before falling asleep or just after waking The pontine center may be continuing to impose muscle paralysis after wakefulness Sleep disorders in children: Night terrors and sleep enuresis (bed-wetting) are associated with SWS Somnambulism (sleepwalking) occurs during stage 3 SWS May persist into adulthood

66. Sleep Disorders People with narcolepsy : Have frequent, intense sleep attacks: Last 5–30 minutes Occur any time of day Occur several times a day; every 90 minutes Do not go through SWS before REM sleep May show cataplexy —a sudden loss of muscle tone, leading to collapse

67. Sleep Disorders Sleep-onset insomnia is a difficulty in falling asleep and can be caused by situational factors, such as shift work or jet lag Sleep-maintenance insomnia is a difficulty in staying asleep and may be caused by drugs or neurological and psychiatric factors. Especially evident in respiratory disorders

68. Sleep Disorders In sleep apnea , breathing may stop or slow down when muscles in the chest and diaphragm relax too much or from changes in the pacemaker respiratory neurons in the brainstem. May be accompanied by snoring Sleep state misperception occurs when people report they haven’t slept even when EEG indicates that they have.

69. Sleep Disorders REM behavior disorder ( RBD ) — organized behavior in a person who appears to be asleep Usually begins after age 50 More common in men May be followed by early symptoms of Parkinson’s disease and dementia Suggests the widespread damage of these diseases begins in the brainstem region that imposes muscle atonia

70. REM or NREM parasomnias? And why?

71. Be sure to wash your brain (plenty) before the exam next week!