1. SLEEP & CIRCADIAN RHYTHMS
Images in these slides were obtained from the following sources:
Carlson, Physiology of Behavior, 9th edition (2007) Allyn and Bacon
Rosenzweig, Leiman and Breedlove, Biological Psychology (2001) Sinaur Associates, Inc

2. SLEEP PHYSIOLOGY PHYSIOLOGICAL MEASURES Electroencephalogram (EEG)
brain waves from scalp surface
Electrooculogram (EOG)
eye movements
Electromyogram (EMG)
muscle tone

3. SLEEP PHYSIOLOGY EEG Waves (wakefulness) beta waves alpha waves
Irregular low amp., high freq. waves (13-30 Hz)
indicative of alert and vigilant activity
alpha waves
regular medium freq. waves (8-12 Hz)
resting quietly, but awake

4. SLEEP PHYSIOLOGY SLEEP STAGES Stage 1: alpha and theta waves (initial)
Stage 2: K complexes, sleep spindles
Stage 3: 20-50% delta (SWS)
Stage 4: > 50% delta (SWS)
REM (emergent stage 1)

5. SLEEP PHYSIOLOGY REM SLEEP
increased cerebral activity, erratic EEG (beta and theta waves)
rapid eye movements
loss of core muscle tone (paralysis)
autonomic arousal (elevated hr, bp, and respiration)
narrative dreams with much visual imagery
initially referred to as “PARADOXICAL SLEEP”

6. SWS VS. REM SLEEP

7. SLEEP CYCLES

8. SLEEP PATTERNS Percent of SWS vs. REM changes with age
Young Adult sleep patterns consist of:
7-8 hours of min. repeating cycles
45-50% of total sleep is stage 2
20% of total sleep is REM sleep
More SWS early in night
Progressive lengthening of REM periods

9. LIFE SPAN CHANGES IN SLEEP
Daily sleep rhythms begin ~ 16 weeks.
Greater % REM in infants and children.
REM component decreases with age.
Total sleep time decreases with age.
Elderly frequently experience insomnia and decreased SWS.

10. LIFE SPAN CHANGES IN SLEEP

11. SLEEP DISORDERS INSOMNIA
affects ~25% of population occasionally, ~9% regularly
No single definition
Insomnia is symptom, not a disease
multiple causes, often iatrogenic
tolerance to sedative-hypnotic drugs
frequent symptom of depression
Other causes: sleep apnea, nocturnal myoclonus, restless legs (PLMD)

12. SLEEP DISORDERS Sleep-onset insomnia Sleep maintenance insomnia
difficulties falling asleep
Sleep maintenance insomnia
frequent awakenings, may be associated with SLEEP APNEA (difficulty breathing while asleep)

13. SLEEP DISORDERS NARCOLEPSY Characteristic Symptoms:
Sleep Attack (5-30 minutes)
Cataplexy
frequently brought on by intense emotions
Immediate REM at sleep onset
Sleep Paralysis
Hypnogogic Hallucinations

14. SLEEP DISORDERS NARCOLEPSY Heritability and Hypocretin (Orexin)
Genetic models in dogs
increased ACh receptors in pons
amygdala and forebrain degeneration
canarc gene (Hypocretin 2 receptors)
Hypocretin gene knockout mouse model
CSF analysis in human narcoleptic patients show diminished hypocretin levels.

15. SLEEP DISORDERS REM SLEEP BEHAVIOR DISORDER
Characterized by failure to exhibit muscle paralysis during REM sleep
Appears to be neurodegenerative disorder with some possible genetic component
Often associated with other neurodegenerative disorders, such as Parkinson’s disease
Usually treated with clonazepam, a benzodiazepine

16. SLEEP DISORDERS
COMMON CHILDHOOD SLEEP DISORDERS ASSOSCIATED WITH SLOW WAVE SLEEP
Pavor Nocturnus (night terrors)
Somnambulism (sleep walking)
Nocturnal Enuresis (bed wetting)

17. SLEEP FUNCTIONS (Why do we sleep?)
Restorative Functions
growth and repair
Adaptive Functions
predator avoidance
energy conservation
Cognitive Functions
learning, unlearning, reorganization

18. COMPARATIVE STUDIES OF SLEEP

19. SLEEP IN MARINE MAMMALS

20. SLEEP DEPRIVATION Early reports of bizarre or psychotic behavior
Wide individual variability (personality and age factors)
Most common effects of sleep deprivation:
increased irritability
decreased concentration
Confusion/disorientation

21. SLEEP DEPRIVATION IN HUMANS
Performance on brief tasks is unimpaired.
Performance on tasks that involve high motivation are generally not impaired.
Sleep Recovery (Randy Gardner story)
11 days (264 hours) sleep deprivation
1st night, ~ 15 hours; stage 4 increased at expense of stage 2
2nd night, ~10 hours; greatest REM recovery
Percentages of sleep recovery not equivalent across all stages: 7% of stages 1 and 2, 68% SWS, 53% REM sleep “made up”

22. SLEEP DEPRIVATION IN NONHUMANS
It is difficult to tease apart effects of sleep deprivation versus stressful effects of the procedure.
Rechtschaffen and Bergmann, 1995
Carousel apparatus with yoked controls
Experimental animals died within days, while controls remained relatively healthy.

23. EFFECTS OF ACTIVITIES ON SLEEP
Effects of Exercise on Sleep
Does the brain recover from day time physical exertion?
Little compelling evidence: People who spend much of their time resting in bed do not sleep less
Effects of Mental Activity on Sleep
Does the brain recover from day time mental exertion?
Some studies have shown that extensive mental activities are followed by normal sleep duration, but increased SWS.

24. FUNCTIONS OF REM SLEEP Theories that REM sleep is required for normal
Mental health
Motivation
Cognitive processing
Interesting links between REM sleep and depression
REM deprivation has antidepressant effects
Most antidepressant drugs also reduce REM sleep.
There’s considerable research on links between REM sleep and learning/memory.

25. REM SLEEP DEPRIVATION
Following REM deprivation, there is a compensatory increase in REM sleep, which seems to suggest REM sleep is a necessary brain function.
Some evidence that REM deprivation can produce cognitive/memory deficits.
Some evidence that REM sleep increases following new learning.

26. NEURAL MECHANISMS OF SLEEP
Basal Forebrain
Brain Stem Reticular Formation
Raphe nucleus (midbrain)
Locus Coeruleus (pons)
Lateral hypothalamus

27. NEURAL MECHANISMS OF SLEEP
Sleep is an active state mediated by at least three neural systems
Forebrain: generates SWS
Reticular Formation: Wakes Forebrain
Pons: Triggers REM sleep

28. NEURAL MECHANISMS OF SLEEP
Bremer (1935)
Encephale isole
Cerveau isole
Moruzzi and Magoun (1949)
Reticular formation
Jouvet (1967)
Raphe system

29. NEURAL MECHANISMS OF SLEEP
BASAL FOREBRAIN
ventral frontal lobe, anterior hypothalamus
lesions abolish SWS
electrical or heat stimulation can induce SWS activity
These neurons are active at sleep onset
Inhibited by NE stimulation

30. NEURAL MECHANISMS OF SLEEP
RETICULAR FORMATION
central core of brain stem
diffuse group of cells extending from medulla to thalamus
electrical stimulation produces arousal, awakens a sleeping animal
lesions produce persistent sleep

31. NEURAL MECHANISMS OF SLEEP
RAPHE NUCLEI
A system of serotonergic neurons along midline of brain stem.
Lesions to Raphe nuclei produce insomnia.
PCPA inhibits 5-HT synthesis and reduces sleep, whereas 5-HT agonists promote sleep

32. NEURAL MECHANISMS OF SLEEP
PONS
crucial for REM sleep components
lesions ventral to Locus Coeruleus abolish REM sleep
electrical or pharmacological stimulation (ACh agonists) can induce or prolong REM sleep
small lesions ventral to LC selectively abolish REM muscle atonia

33. NEUROTRANSMITTERS AND SLEEP

34. CIRCADIAN RHYTHMS DEFINITION EXAMPLES 24 hr. endogenous cycles
sleep/wake cycle
body temperature
hormone secretion
drug sensitivity

35. LABORATORY STUDIES OF CIRCADIAN RHYTHMS

36. CIRCADIAN RHYTHMS TERMINOLOGY Free Running Period Entrainment
Zeitgeber
Phase Shifts
phase advances: acceleration of circadian rhythm
phase delays: deceleration of circadian rhythm

37. CIRCADIAN RHYTHMS Circadian Timing Mechanisms
Internal desynchronization of S-W cycle and body temp. cycle suggest separate timing mechanisms.
Common Examples of Phase Shifts
Jet Lag results from phase shifts in circadian rhythms as a result of traveling across time zones.
Shift workers often forced to adjust S-W cycle. Such disruptions may affect health and productivity.

38. NEURAL MECHANISMS OF CIRCADIAN RHYTHMS

39. SUPRACHIASMATIC NUCLEUS
Experimental Research on SCN involvement in circadian rhythms
Large lesions of hypothalamus disrupt circadian cycles of activity in rats. (Richter, 1967)
Lesions specific to SCN disrupt periodicity of sleep/wake cycle
SCN displays circadian cycles of electrical, metabolic, and biochemical activity.
Fetal tissue transplants in hamsters
Fetal tissue from 20 hour donor implanted in 25 hour recipient after SCN lesion.
Recipient becomes entrained to 20 hour cycle

40. SUPRACHIASMATIC NUCLEUS