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Normal Sleep Architecture


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Normal Sleep Architecture

  1. 1. ‫النوم‬...‫هللا‬ ‫آيات‬‫من‬ ‫آية‬!
  2. 2. Normal Sleep Architecture
  3. 3. Polysomnography
  4. 4. Measuring Sleep activity
  5. 5. Sleep Academic Award 9
  6. 6. Equipment for EEG Recording (1926)
  7. 7. • A hypnogram is a form of polysomnography; it is a graph that represents the stages of sleep as a function of time. • It was developed as an easy way to present the recordings of the brain wave activity from an electroencephalogram (EEG) during a period of sleep. • It allows the different stages of sleep: rapid eye movement sleep (REM) and non-rapid eye movement
  8. 8. • NREM sleep can be further classified into NREM stage 1, 2 and 3. • The previously considered 4th stage of NREM sleep has been included within stage 3; this stage is also called slow wave sleep (SWS) and is the deepest stage of sleep. • Each of the three NREM stages as well as the period of REM sleep and the awake state can be determined and displayed on a hypnogram
  9. 9. Discovery of REM sleep 1951 Kleitman & Aserinsky
  10. 10. TYPES OF SLEEP • There are two types of sleep: 1. Non Rapid Eye Movement Sleep ( NREM ) [Slow Wave Sleep- Dreamless]. 2. Rapid eye movement Sleep ( REM ) [Dreamful]. • Both types alternate with each other. • Surprisingly, they are as different from each other as either is from waking
  11. 11. ©John Wiley & Sons, Inc. 2007 Huffman: Psychology in Action (8e) Normal Sleep Stages • NREM (Non-Rapid-Eye-Movement) Sleep: —Stage 1 (lightest sleep) —Stage 2 (deeper sleep) —Stages 3 and 4 (deepest sleep) • REM (Rapid-Eye-Movement) Sleep: —Light sleep--also called paradoxical sleep
  12. 12. • Stage 1 Transition • Stage 2 Light Sleep • Stage 3 & 4 Slow wave - deep sleep • Stage 5 REM sleep Normal Sleep Stages
  13. 13. STAGES OF SLEEP 5 Stages •Non-REM Sleep - Stage 1 - Stage 2 - Stage 3 } Slow Wave Sleep - Stage 4 } •REM Sleep (motor activity is inhibited) Deeper Sleep
  14. 14. Normal Sleep Stages and Function Vander et al. Consciousness and behavior. In: Human Physiology. 1990. States Function Active state of brain functions in learning and memory Body’s rest and metabolic restoration Phasic eye movements Loss of muscle tone EEG neutral Stage 3 Stage 4 (REM) Stage 1 Stage 2 (NREM)
  15. 15. NREM Sleep 4 stages of NREM Sleep • Stages 1 and 2 – Light sleep stages • Stages 3 and 4 – Deep sleep or slow wave sleep stages
  16. 16. Restorative stages of sleep (Stages 3 and 4 and REM )
  17. 17. Normal Sleep Hypnogram
  18. 18. Sleep Architecture in young Adults •Wakefulness in sleep, <5% of night •Stage I 2 - 5% Stage II 45 - 55% Stage III 3 - 8% Stage IV 10 - 15%  NREM 75 - 80% •REM 20 - 25% in 4-6 episodes
  19. 19. Human Sleep is Cyclical
  20. 20. Normal sleep hypnogram
  21. 21. Normal Physiology - Basics • Non-REM Sleep – Stage 1: very light, easy to arouse – Stage 2: most of the night’s sleep – Stage 3,4: slow wave, deeper sleep • REM Sleep – EEG similar to stage 1 – Low/absent muscle tone – Dreaming occurs here – Greatest cardiac and respiratory instability
  22. 22. SLEEP PHYSIOLOGY •REM and non-REM sleep alternate cyclically •REM sleep: - 20-30min every 90-120 min - increases later in night
  23. 23. Normal Physiology - Basics • Sleep Architecture – REM latency is about 90 minutes (wide variation) • Very short in narcolepsy – REM normally occurs every 90 to 120 minutes – More stage 3,4 in first half of night, more REM 2nd half – Brief awakenings (30 sec) common, not usually remembered – Brief arousals (3 sec) are normal
  24. 24. © 2004 John Wiley & Sons, Inc. Huffman: PSYCHOLOGY IN ACTION, 7E
  25. 25. Typical Nightly Sleep Stages Hours of sleep Minutes of Stage 4 and REM 1 2 3 4 5 6 7 8 0 10 15 20 25 5 Decreasing Stage 4 Increasing REM
  26. 26. Sleep Cycles • Usually about 10-30 minutes to fall asleep – <5 minutes indicates excessive sleepiness – >30 minutes due to lack of sleepiness, emotional stress, environmental disturbances, medication, illness, or pain • Full sleep cycle: – Stage one – Stages 2-4 – Return to stage 3 then stage 2 – From stage 2 comes REM – End of REM in the conclusion of the first cycle • Normal night’s sleep = 4-6 cycles of sleep
  27. 27. Normal Sleep Cycle • Normal sleep cycle. The sleeper progresses through Stages 1, 2, 3, and 4; followed by a return to Stage 3 and 2. • From Stage 2 the sleeper moves into REM sleep. The end of REM sleep ends the first sleep cycle. • From REM sleep, the sleeper moves back to Stage 2 and a new sleep
  28. 28. • In a normal night's sleep, a sleeper begins in stage 1, moves down through the stages, to stage 4, then back up through the stages, with the exception that stage 1 is replaced by REM, then the sleeper goes back down through the stages again. • One cycle, from stage 1 to REM takes approximately ninety minutes. This cycle is repeated throughout the night, with the length of REM periods increasing, and the length of delta sleep decreasing, until during the last few cycles there is no delta sleep at all.
  29. 29. Sequence of sleep stages on three representative nights
  30. 30. Sleep Academic Award 39 Sleep States of Being (adults) REM Sleep ~20% of night NREM Sleep ~80% of night Wake 2/3 of life
  31. 31. Sleep-Wake Cycle Wakefulness REM sleep 18.00 20.00 22.00 24.00 02.00 04.00 06.00 08.00 10.00 12.00 14.00 16.00 MT W REM 1 2 3/4 Time of day Sleepstage Adapted from Rogers et al. Sleep. 1994;17:590. NREM stage 1-4 Awake Stage 1 and REM Stage 2 Stage 3 Stage 4 EEG Recordings
  32. 32. Stages of Wakefulness and Sleep • Wakefulness – Beta wave and alpha wave activity • Brain Activity During Sleep – Alternating periods of rapid-eye-movement (REM) sleep and Non-REM (NREM) sleep – Stage 1 NREM– theta waves, myoclonia – Stage 2 NREM– sleep spindles, K-complex – Stage 3 NREM– some delta waves – Stage 4 NREM– 50 % delta waves – REM
  33. 33. ©John Wiley & Sons, Inc. 2007 Huffman: Psychology in Action (8e) Stages of Sleep & Brain Waves
  34. 34. Sleep Stages • Sleep architecture follows a pattern of alternating REM (rapid eye movement) and NREM (non-rapid eye movement) sleep throughout a typical night in a cycle that repeats itself about every 90 minutes. 1. NREM sleep (75-80% of sleep in healthy young adults). 2. REM sleep (20-25% of sleep in healthy young adults). • These stages are defined by distinct
  35. 35. Quiet sleep • Sleep specialists have called non-REM or quiet sleep “an idling brain in a movable body.” • During this phase, thinking and most physiological activities slow down, but movement can still occur, and a person often shifts position while sinking into deeper stages of sleep
  36. 36. • When you are awake, billions of brain cells receive and analyze sensory information, coordinate behavior, and maintain bodily functions by sending electrical impulses to one another. If you’re fully awake, the EEG will record a messy, irregular scribble of activity. • Once your eyes are closed and your nerve cells no longer receive visual input, brain waves settle into a steady and rhythmic pattern of about 10 cycles per second. This is the alpha-wave pattern, characteristic of calm, relaxed wakefulness. • The transition to quiet sleep is a quick one that might be likened to flipping a switch — that is, you are either awake (switch on) or asleep (switch off) Quiet sleep
  37. 37. • Non-REM sleep may be viewed as a period of relative low brain activity during which the regulatory capacity of the brain is actively ongoing and in which body movements are preserved • Non-REM sleep is further divided into: ¯ Stage 1 - Stage 2 - Stage 3 - Stage 4
  38. 38. Stage 1 (Transition to sleep) —Stage 1 sleep (2-5%) which occurs at the sleep- wake transition and is often referred to as “light sleep” —Stage 1 lasts about five minutes. —Eyes move slowly under the eyelids, muscle activity slows down —You are easily awakened. —if awakened people say they weren’t asleep. —E.E.G. findings: Alpha waves diminish and Theta waves appear on EEG.
  39. 39. —In making the transition from wakefulness into light sleep, you spend about five minutes in stage N1 sleep. —On the EEG, the predominant brain waves slow to four to seven cycles per second, a pattern called theta waves. —Body temperature begins to drop, muscles relax, and eyes often move slowly from side to side. —People in stage N1 sleep lose awareness of their surroundings, but they are easily jarred awake. —However, not everyone experiences stage N1 sleep in the same way: if awakened, one person might Stage 1 (Transition to sleep)
  40. 40. —Stage 2 sleep is the first stage of true sleep. —lasts 10 to 25 minutes. you spend about half the night (45-55) in stage 2 sleep. —Stage 2 sleep is usually considered the initiation of “true” sleep , This stage involves the following : —Your eyes are still, and your heart rate and breathing are regular slower than when awake , body temperature drops —The person experiences only light sleep. —It is a little harder to awake the person. Stage 2: Light Sleep
  41. 41. —In Stage 2 sleep , EEG tracings is characterized by bursts of rhythmic rapid EEG activity called sleep spindles (fluctuating episodes of fast activity) and high amplitude slow wave spikes called K- complexes —Scientists think that K-complex, represents a sort of built-in vigilance system that keeps you poised to awaken if necessary. —K-complexes can also be provoked by certain sounds or other external or internal stimuli. Stage 2 : Light Sleep
  42. 42. Deep Sleep • Stage 3 sleep is usually combined with stage 4 sleep and usually constitutes 12-18% of sleep. • During this stage, known as deep sleep or slow- wave sleep, the brain becomes less responsive to external stimuli, making it difficult to wake the sleeper. • Deep sleep seems to be a time for your body to renew and repair itself.
  43. 43. Deep Sleep • Typically during this stage: 1. Large, slow brain waves called delta waves become a major feature on the EEG. 2. Breathing becomes more regular. Blood pressure falls, and pulse rate slows to about 20% to 30% below the waking rate. 3. Blood flow is directed less toward your brain. 4. At the beginning of this stage, the pituitary gland releases a pulse of growth hormone that stimulates tissue growth and muscle repair.
  44. 44. oStages 3 and 4 sleep which are otherwise know as “deep” sleep, slow wave sleep, or delta sleep and during which the highest arousal threshold (most difficult to awaken) also occurs. oDelta sleep is generally considered the most restorative stage of sleep oThe deepest stage of sleep. Brain waves are extremely slow. Blood flow is directed away from the brain and towards the muscles, restoring physical energy.
  45. 45. • Note: Most sleep during each night is of a slow wave Lasts for 80=90 minutes. • Dreams / night mare even occur. • The difference is that the dreams in slow wave sleep are not remembered but in REM, dreams can be remembered. Deep Sleep
  46. 46. • Normally, young people spend about 20% of their sleep time in deep sleep lasting, but deep sleep is nearly absent in most people over age 65. • Someone whose deep sleep is restricted will wake up feeling less refreshed. • When a sleep-deprived person gets some sleep, he or she will pass quickly through the lighter sleep stages and spend a greater proportion of time in deep sleep, suggesting that deep sleep fills an essential role in a person’s optimal physical functioning.
  47. 47. Stages 3 and 4  Deepest and most restorative sleep  Blood pressure drops  Breathing becomes slower  Muscles are relaxed  Blood supply to muscles increases  Tissue growth and repair occurs  Energy is restored  Hormones are released, such as: Growth hormone, essential for growth and development, including muscle development Deep Sleep
  48. 48. PHYSIOLOGIC CHANGES DURING NREM AUTONOMIC NERVOUS SYSTEM • Increased parasympathetic tone and decreased sympathetic activity in NREM sleep. GASTRIC FUNCTION: In NREM, failure of inhibition of gastric secretion in 1st 2 hours of sleep; overall decrease in gastric motility during sleep. • Swallowing is suppressed in NREM, stage 3 with prolonged gastric mucosa exposure to reflux. • In NREM there is decrease in core body temperature by due to vasodilatation, lowest at third sleep cycle. ENDOCRINE: In NREM, growth hormone and prolactin secretion is increased. In REM certicotropi-cortisol rhythm is increased in the morning.
  49. 49. •Upon reaching stage 4 and after about 80 to 100 minutes of total sleep time, sleep lightens, returns through stages 3 and 2 •REM sleep emerges, characterized by EEG patterns that resemble beta waves of alert wakefulness – Muscles most relaxed – Rapid eye movements occur – Dreams occur •Four or five sleep cycles occur in a typical night’s sleep; less time is spent in slow-wave, more is spent in REM
  50. 50. REM Sleep (“brain on, body off”) —Rapid eye movements —Wakeful EEG pattern —Increased cerebral blood flow —Absent spinal reflexes —Associated with dreaming —REM sleep usually constitutes 20-25% of sleep in 4 to 6 episodes.
  51. 51. REM ( RAPID EYE MOVEMENT) SLEEP, PARADOXICAL SLEEP, DESYNCHRONIZED SLEEP • 5-30 minutes long, every 90 minutes; • ↓ muscle tone; • ↑ brain metabolism ( as much as 20 % ); • Irregular heart and respiratory rate; • Rapid eye movements; • Less restful, desynchronised; • Associated with psychical activities, such as dreaming.
  52. 52. REM ( RAPID EYE MOVEMENT) SLEEP, PARADOXICAL SLEEP, DESYNCHRONIZED SLEEP Bouts of REM sleep last for 5 to 30 min & usually appear on average every 90 minutes; As the person becomes more rested during the night, the durations of the REM bouts ↑ REM characteristics: 1. Active dreaming 2. The person is more difficult to arouse by sensory stimuli than during the deep slow- wave sleep & people usually awaken spontaneously during a REM episode; 3. Muscle tone is exceedingly depressed – strong inhibition of the spinal muscle control areas; 4. Heart rate & respiratory rate become irregular; 5. Brain is ↑ active & brain waves are similar to those of wakefulness.
  53. 53. REM sleep is characterized by • paralysis or nearly absent muscle tone (except for control of breathing), Body becomes immobile and relaxed, as muscles are turned off • high levels of cortical activity that are associated with dreaming, irregular respiration and heart rate, and episodic bursts of phasic eye movements that are the hallmark of REM sleep. • First occurs about 90 minutes after falling asleep and recurs about every 90 minutes, getting longer later in the night
  54. 54. • REM sleep sets the stage for dreams. Our eyes are scanning back and forth, but our skeletal muscles are paralyzed, Skeletal muscle atonia during REM , perhaps to keep us from acting out our dreams. • A typical night’s sleep consists of four or five REM/non-REM cycles with occasional, brief episodes of wakefulness. • Most Stage 4 sleep occurs during the first two to three hours of sleep. As morning approaches, REM sleep occupies an increasing share of slumber. REM sleep (Dream sleep)
  55. 55. Dreaming (REM) sleep • Dreaming occurs during REM sleep, which has been described as an “active brain in a paralyzed body.” Here is what happens: • Your brain races, thinking and dreaming, as your eyes dart back and forth rapidly behind closed lids. • Your body temperature rises. Your blood pressure increases, and your heart rate and breathing speed up to daytime levels.
  56. 56. • The sympathetic nervous system, which creates the fight-or-flight response, is twice as active as when you’re awake. • Despite all this activity, your body hardly moves, except for intermittent twitches; muscles not needed for breathing or eye movement are quiet. Dreaming (REM) sleep
  57. 57. • In REM, there is penile erection and clitoral engorgement. • They usually bear little relationship to dream content and do not correlate with sensual dreaming. • The ability to obtain normal erection is used to distinguish between physical and psychological impotence.
  58. 58. • Non-REM and REM sleep alternate throughout the night in cycles of about 90-110 minutes. • Brief arousals normally followed by a rapid return to sleep often occur at the end of each sleep cycle (4-6 times per night). • The relative proportion of REM and non-REM sleep per cycle changes across the night, such that slow wave sleep predominates in the first third of the night and REM sleep in the last third.
  59. 59. • About three to five times a night, or about every 90 minutes, a sleeper enters REM sleep. The first such episode usually lasts only for a few minutes, but REM time increases progressively over the course of the night. The final period of REM sleep may last a half-hour. • Normally, REM sleep makes up about 25% of total sleep in young adults. • If someone who has been deprived of REM sleep is left undisturbed for a night, he or she enters this stage earlier and spends a higher proportion of sleep time in it — a phenomenon called REM rebound.
  60. 60. REM Sleep —Just as deep sleep renews the body, REM sleep renews the mind. —REM sleep plays a key role in learning and memory. —During REM sleep, your brain consolidates and processes the information you have learned during the day, forms neural connections that strengthen memory, and replenish its supply of neurotransmitters, including feel-good chemicals such as serotonin and dopamine that boost your mood during the day.
  61. 61. • During REM (dreaming) sleep, the body is still, but the mind is racing. • Time spent in REM sleep increases as the night progresses. • REM sleep restores the mind , It is important for both learning and memory. REM Sleep
  62. 62. ‫بالموت‬ ‫النوم‬ ‫عالقة‬ •‫أو‬ ‫األنفس‬ ‫يقبض‬ ‫هللا‬ ‫إن‬‫وي‬ ، ‫بالموت‬ ‫آجالها‬ ‫انقضاء‬ ‫حين‬ ‫األرواح‬‫سمى‬ ‫من‬ ‫األرواح‬ ‫بقبض‬ ‫المكلفة‬ ‫المالئكة‬ ‫طريق‬ ‫عن‬ ‫الكبرى‬ ‫الوفاة‬ ‫ذلك‬ ‫ل‬ ‫التي‬ ‫األنفس‬ ‫يتوفى‬ ‫وكذلك‬ ، ‫باألجساد‬ ‫تعلقها‬ ‫فتقطع‬ ‫األبدان‬ِ‫ت‬‫يأ‬ ‫م‬ ‫بالمو‬ ‫للنائمين‬ ً‫ا‬‫تشبيه‬ ‫وذلك‬ ، ‫المنام‬ ‫عند‬ ‫الصغرى‬ ‫الوفاة‬ ‫أجلها‬، ‫تى‬ •‫تعالى‬ ‫قال‬[ :ْ‫و‬َ‫م‬ َ‫ين‬ ِ‫ح‬ َ‫س‬ُ‫ف‬ْ‫ن‬َ‫أل‬‫ا‬ ‫ى‬َّ‫ف‬َ‫و‬َ‫ت‬َ‫ي‬ ُ‫هللا‬‫ي‬ِ‫ف‬ ْ‫ت‬ُ‫م‬َ‫ت‬ ْ‫م‬َ‫ل‬ ‫ي‬ِ‫ت‬َّ‫ل‬‫ا‬َ‫و‬ ‫ا‬َ‫ه‬ِ‫ت‬‫ا‬َ‫ه‬ِ‫ام‬َ‫ن‬َ‫م‬ ُ‫ي‬َ‫و‬ َ‫ت‬ ْ‫و‬َ‫م‬‫ال‬ ‫ا‬َ‫ه‬ْ‫ي‬َ‫ل‬َ‫ع‬ ‫ى‬َ‫ض‬َ‫ق‬ ‫ي‬ِ‫ت‬َّ‫ل‬‫ا‬ ُ‫ك‬ِ‫س‬ْ‫م‬ُ‫ي‬َ‫ف‬‫م‬َ‫س‬ُ‫م‬ ٍ‫ل‬َ‫ج‬َ‫أ‬ ‫ى‬َ‫ل‬ِ‫إ‬ ‫ى‬َ‫ر‬ْ‫خ‬ُ‫أل‬‫ا‬ ُ‫ل‬ِ‫س‬ْ‫ر‬‫ى‬] {‫مر‬ُّ‫ز‬‫ال‬:42}‫هللا‬ ‫أن‬ ‫يتضح‬ ‫اآلية‬ ‫هذه‬ ‫خالل‬ ‫من‬ ،–‫سبحانه‬–‫يمسك‬ ‫إل‬ ‫يردها‬ ‫فال‬ ، ‫الحقيقي‬ ‫الموت‬ ‫عليها‬ ‫قضى‬ ‫التي‬ ‫واألرواح‬ ‫األنفس‬‫ى‬ ‫حين‬ ‫األجساد‬ ‫إلى‬ ‫النائمة‬ ‫النفس‬ ‫ويرسل‬ ، ‫فيه‬ ‫كانت‬ ‫الذي‬ ‫الجسد‬‫اليقظة‬ ‫الحقيق‬ ‫الموت‬ ‫وقت‬ ‫وهو‬ ‫مسمى‬ ‫أجل‬ ‫إلى‬ ‫إحساسها‬ ‫إليها‬ ‫يعيد‬ ‫بأن‬ ،‫ي‬. ‫ج‬ ، ‫المنير‬ ‫التفسير‬24‫ص‬ ،22.
  63. 63. Characteristics of REM &non-REM sleep Sleep activity REM sleep Non-REM sleep Eye movement Rapid Slow (drowsiness) Body movement Muscle twitches Muscle relaxation Vital signs Fluctuating Stable Muscle tone decreased Some tone in postural muscle Penile erection common Rare Dreams Common Rare EEG Low voltage Spindles, V-waves, K- complexes, slow waves Percentage-adults 20-25 75-80 Percentage-infants 50 50
  64. 64. Sleep Cycle • Movement from Stage 1 to Stage 4 and back to Stage 1 • REM Sleep substitutes for Stage 1 sleep during cycle • Between 90-110 minutes to move through an entire cycle • Each night = 3 to 5 complete cycles
  65. 65. Sleep architecture • During the night, a normal sleeper moves between different sleep stages in a fairly predictable pattern, alternating between quiet sleep (non-REM) and dreaming sleep (REM). When these stages are charted on a diagram, called a hypnogram , Sleep experts call this pattern sleep architecture. • In a young adult, normal sleep architecture usually consists of four or five alternating non-REM and REM periods. Most deep sleep occurs in the first half of the night. As the night progresses, periods of REM sleep get longer and alternate with stage N2 light sleep. Later in life, the sleep skyline will change, with less deep sleep, more stage N1 sleep drowsiness, and more awakenings.
  66. 66. •Sleep cycles emerge during prenatal development. •Newborns sleep about 16 hours per day. •By age 2, 75-minute sleep cycles are experienced. •By age 5, typical 90-minute sleep cycles of alternating REM and NREM sleep emerge. •Deeper slow-wave sleep decreases with age. •Time in REM sleep increases during childhood and adolescence, remains stable throughout adulthood, and decreases during late adulthood.
  67. 67. Normal Sleep Cycles Children Young Adults Elderly
  68. 68. Human Sleep Exhibits Different Stages • In a typical night of young adult sleep: —Sleep time ranges from 7-8 hours. —45-50% is stage 2 sleep, 20% is REM sleep. —Cycles last 90-110 minutes, but cycles early in the night have more stage 3 and 4 SWS, and later cycles have more REM sleep.
  69. 69. • At age 20, we spend an average of 7.5 hours a night sleeping —with about 90 minutes each of REM and deep sleep • By the time we’re 60, we’re only sleeping 6.2 hours a night. Our Sleep Patterns Change across the Life Span
  70. 70. Our Sleep Patterns Change across the Life Span • Mammals sleep more during infancy than in adulthood. • Infant sleep is characterized by: — Shorter sleep cycles — More REM sleep – 50%, which may provide essential stimulation to the developing nervous system
  71. 71. Newborn and Infant Sleep • Newborn sleep has 2 stages 50% “quiet or non-rapid eye movement (NREM) sleep” and 50% “active or rapid eye movement (REM) sleep REM sleep appears to promote brain development. • Total sleep time = 16 to 17 hours / 24 hour period with frequent awakenings for feeding and nurturing
  72. 72. Sleep in the Elderly
  73. 73. Normal Sleep and Normal Aging: Sleep Efficiency Men Women Age SleepEfficiency (%TimeinBedSleeping) Changes with age
  74. 74. Normal Sleep and Normal Aging: Less Deep Sleep
  75. 75. Typical Nightly Sleep Stages 0 1 2 3 4 5 6 7 4 3 2 1 Sleep stages Awake Hours of sleep REM
  76. 76. • As people age, total time asleep declines, and number of awakenings increases. • The most dramatic decline is the loss of time spent in stages 3 and 4 • by age 90 stages 3 and 4 have disappeared Our Sleep Patterns Change across the Life Span
  77. 77. Age-Related Changes Non-REM ◦ Less slow wave sleep (stage 3 and 4), may be entirely absent, easier to awaken REM ◦ Shorter REM latency ◦ Decreased REM percentage and duration Architecture ◦ Increased overall sleep latency ◦ More awakenings/arousals = less sleep efficiency ◦ Less sleep in 24 hour period ◦ Reduced sleep latency during day – harder to stay awake Espiritu JR. Clin Geriatr Med 2008;24:1-14.
  78. 78. Age-Related Changes • Sleep during the night changes with increasing age: – Less deep sleep and more lighter sleep – More difficulty maintaining sleep due to arousals and awakenings – Sleep is less efficient and more fragmented • The internal biological clock shifts to earlier bed and wake times • Older persons experience a higher prevalence of medical conditions and take meds that interrupt sleep and are associated with sleep problems/disorders • Older persons experience a higher prevalence of sleep disorders
  79. 79. Sleep changes and aging • Aging is associated with malfunction or decrease in sensitivity of the SCN to environmental cues to adjust circadian rhythm to a natural 24-hour day/night cycle • More fragmented sleep • Increased in stage 1 and 2 sleep with more fragmented REM sleep indicating more dreaming • Slow wave sleep is reduced
  80. 80. ©John Wiley & Sons, Inc. 2007 Huffman: Psychology in Action (8e) Sleep Over the Life Span
  81. 81. Human Sleep Patterns Change with Age
  82. 82. Vertebrate Species Differ in Their Patterns of Sleep • For laboratory rats, one sleep cycle lasts an average of 10–11 minutes • for humans, one cycle lasts 90–110 minutes. • Across species, cycle duration is inversely related to metabolic rate; that is, small animals, which tend to have high metabolic rates , have short sleep cycles, and large species have long sleep cycles.
  83. 83. Amounts of Different Sleep States in Various Mammals
  84. 84. ©John Wiley & Sons, Inc. 2007 Huffman: Psychology in Action (8e) NREM and REM Sleep in Cats • Can you identify which photo was taken while this cat was in REM Sleep?
  85. 85. Thank You !