The document discusses biological rhythms and sleep. It describes circadian rhythms regulated by the suprachiasmatic nucleus and synchronized to the light-dark cycle via the retinohypothalamic pathway. Sleep has two states - slow-wave sleep and REM sleep - which alternate in cycles. Neural circuits in the forebrain, brainstem, pons, and hypothalamus regulate sleep-wake states. Sleep disorders include insomnia, sleep apnea, narcolepsy, and REM behavior disorder. Maintaining good sleep hygiene can help treat disorders.

1. Ch10: Biological Rhythms
& Sleep
➔Biological Rhythms
➔Sleep Patterns
➔Neural Systems & Sleep
➔Sleep Disorders

2. BIOLOGICAL RHYTHMS
• BIOLOGICAL RHYTHMS: regular fluctuations in
a living process
• CIRCADIAN RHYTHMS: 24 hour fluctuation
periods
– DIURNAL
– NOCTURNAL

3. BIOLOGICAL RHYTHMS
• FREE-RUNNING: maintaining a
cycle with no external cues
• PERIOD: time between
successive cycles
• PHASE SHIFT : shift in response
to a synchronizing stimulus
(ZEITGEBER)

4. Figure 10.2 How Activity Rhythms Are
Measured (Part 1)
BIOLOGICAL RHYTHMS

5. BIOLOGICAL RHYTHMS
• SUPRACHIASMATIC NUCLEUS
(SCN): in the hypothalamus; the
body’s biological clock
– SCN-lesioned animals show
disruption
– Isolated cells stay synchronized
– Transplant studies

6. BIOLOGICAL RHYTHMS
RETINOHYPOTHALAMIC PATHWAY: brings info from the eye
to the SCN
1. PHOTOSENSITIVE RETINAL GANGLION CELLS (pRGCS),
contain MELANOPSIN, a photopigment
2. pRGCs also receive info about light from rods/cones
3. pRGCs send information directly to the SCN

7. 1. Clock & cycle proteins form a dimer
2. Clock/Cycle dimer binds to DNA,
increasing transcription of per & cry
genes, which create proteins Per and
Cry
3. Per & Cry bind together and inhibit the
Clock/Cycle dimer, slowing transcription
of per and cry
4. Per & Cry proteins break down,
releasing Clock/Cycle from inhibition
5. The cycle repeats every 24 hours
BIOLOGICAL RHYTHMS
1
2
3 4
5

9. BIOLOGICAL RHYTHMS
• Gene mutations show how
important the clock is to
behavior in constant conditions:
– Tau mutations = shorter period
– Double Clock = severe
arrhythmia

10. BIOLOGICAL RHYTHMS
In humans:
– Sleep is synchronized to external
events
– Free-running period = 25 hours
– Clock gene variation = cycle traits

11. Ch10: Biological Rhythms
& Sleep
➔Biological Rhythms
➔Sleep Patterns
➔Neural Systems & Sleep
➔Sleep Disorders

12. SLEEP PATTERNS
• ELECTROENCEPHALOGRAPHY (EEG): records
activity in the brain through large electrodes on
the scalp

13. SLEEP PATTERNS
• Two classes of sleep:
– SLOW-WAVE SLEEP (SWS): three stages of slow-
wave EEG activity
• AKA non-REM
– RAPID-EYE-MOVEMENT SLEEP (REM): short, fast-
EEG waves, relaxed muscle tension, and rapid eye
movements

14. SLEEP PATTERNS
• EEG of an awake person:
– High frequency, low amplitude waves
– DESYNCHRONIZED EEG (beta activity)

15. SLEEP PATTERNS
STAGES OF SLOW-WAVE SLEEP
• STAGE 1 SLEEP
– ALPHA RHYTHM: slower waves, relaxation
– VERTEX SPIKES
– Reduced heart rate & muscle tension, slow eye
rolls

16. SLEEP PATTERNS
STAGES OF SLOW-WAVE SLEEP
• STAGE 2 SLEEP
– SLEEP SPINDLES: sudden bursts of activity
– K-COMPLEXES: sharp negative EEG potentials

17. SLEEP PATTERNS
STAGES OF SLOW-WAVE SLEEP
• STAGE 3 SLEEP
– Continued sleep spindles
– DELTA WAVES: large-amplitude, very slow waves
(one per second)

18. SLEEP PATTERNS
• REM SLEEP
– Active EEG (small-amplitude, high-frequency
waves)
– ATONIA: absence of muscle tone, brainstem
inhibits motor signals
– PARADOXICAL SLEEP: active mind, still body

19. SLEEP PATTERNS

20. SLEEP PATTERNS

21. SLEEP PATTERNS

22. SLEEP PATTERNS
• Vivid dreams occur during REM sleep:
– Visual imagery
– Sense that the dreamer is “there”
• NIGHTMARES: frightening dreams that wake you up
• NIGHT TERRORS: sudden arousals from stage 3 SWS,
with fear and autonomic activity

23. • REM sleep evolved in some vertebrates:
– Most mammals & birds display both REM and SWS
– Dolphins & birds: brain hemispheres take turns in SWS
SLEEP PATTERNS

24. SLEEP PATTERNS

25. Figure 10.17 The Typical Pattern of
Sleep in an Elderly Person
SLEEP PATTERNS

26. SLEEP PATTERNS
• SLEEP DEPRIVATION:
– Irritability
– Difficulty concentrating
– Disorientation
• 4-6 hours per night for 2 weeks = deficits on
attention tasks & reaction time
• Effects vary with age and other factors

27. SLEEP PATTERNS
• SLEEP RECOVERY: sleeping more than normal,
after a period of deprivation

28. SLEEP PATTERNS
• Total sleep deprivation can be fatal
– Harms the immune system and leads to death
– FATAL FAMILIAL INSOMNIA

29. SLEEP PATTERNS
1. Energy Conservation
– Physiological processes
are reduced
– Smaller animals sleep more
FOUR FUNCTIONS OF SLEEP

30. SLEEP PATTERNS
2. Niche Adaptation
– ECOLOGICAL NICHE
– Sleep helps animals avoid predators
– Animals sleep when they are most
vulnerable
FOUR FUNCTIONS OF SLEEP

31. SLEEP PATTERNS
3. Body Restoration
– Replenishing metabolic requirements
– Releasing growth hormone
– Immune function
FOUR FUNCTIONS OF SLEEP

32. SLEEP PATTERNS
4. Memory Consolidation
– Sleep after learning improves recall
• Reduces interference
• Slows memory decay
• Aids in consolidation
FOUR FUNCTIONS OF SLEEP

33. SLEEP PATTERNS
4. Memory Consolidation
– Sleep after
learning
improves
recall
FOUR FUNCTIONS OF SLEEP

34. Ch10: Biological Rhythms
& Sleep
➔Biological Rhythms
➔Sleep Patterns
➔Neural Systems & Sleep
➔Sleep Disorders

35. NEURAL SYSTEMS & SLEEP
• Sleep is an active state regulated by:
– Forebrain
– Brainstem
– Pons
– Hypothalamus

36. NEURAL SYSTEMS & SLEEP
ISOLATED BRAIN: incision
between the medulla
and spinal cord
Signs of sleep and
wakefulness are still
observed.
THE FOREBRAIN SYSTEM

37. NEURAL SYSTEMS & SLEEP
ISOLATED FOREBRAIN:
incision in the midbrain
Constant SWS, without
REM or waking.
THE FOREBRAIN SYSTEM

38. NEURAL SYSTEMS & SLEEP
• BASAL FOREBRAIN: generates the constant
SWS activity in the forebrain
• Active at sleep onset and releases GABA
• GABA activates receptors in the nearby
TUBEROMAMMILLARY NUCLEUS in the
hypothalamus
THE FOREBRAIN SYSTEM

39. NEURAL SYSTEMS & SLEEP
• RETICULAR FORMATION: brainstem region
involved in arousal
– Activates the cortex
– Electrical stimulation wakes up sleeping animals
– Lesions increase sleep
THE BRAINSTEM SYSTEM

40. NEURAL SYSTEMS & SLEEP
• An area of the PONS, is responsible for REM sleep
• Inhibits motoneurons, disabling the motor system during REM
THE PONTINE SYSTEM

41. NEURAL SYSTEMS & SLEEP
• NARCOLEPSY: a disorder that involves…
– Frequent sleep attacks & excessive daytime
sleepiness
– Going directly into REM sleep
– CATAPLEXY: sudden loss of muscle tone, leading
to collapse
THE HYPOTHALAMIC SYSTEM

42. Figure 10.25 Canine Narcolepsy
NEURAL SYSTEMS & SLEEP
THE HYPOTHALAMIC SYSTEM

43. NEURAL SYSTEMS & SLEEP
• Narcoleptic dogs have a mutant gene for an
OREXIN receptor
– Orexin prevents the transition from wakefulness
directly into REM sleep
– Interfering with orexin signaling leads to
narcolepsy
THE HYPOTHALAMIC SYSTEM

44. Figure 10.26 Neural Degeneration in
Humans with Narcolepsy
NEURAL SYSTEMS & SLEEP
THE HYPOTHALAMIC SYSTEM

45. NEURAL SYSTEMS & SLEEP
• Orexin neurons project to:
– Other sleep system centers
– Tuberomammillary nucleus, whose inhibition
induces SWS
• The hypothalamus seems to contain a orexin
sleep center
THE HYPOTHALAMIC SYSTEM

46. Figure 10.23 Brain Mechanisms
Underlying Sleep
NEURAL SYSTEMS & SLEEP
Forebrain System
Pontine System
Brainstem System
Hypothalamic System

47. Ch10: Biological Rhythms
& Sleep
➔Biological Rhythms
➔Sleep Patterns
➔Neural Systems & Sleep
➔Sleep Disorders

48. SLEEP DISORDERS
• Sleep disorders in children:
– Night terrors and SLEEP ENURESIS (bedwetting)
are associated with SWS
– SOMNAMBULISM (sleepwalking): occurs during
stage 3 SWS, and may persist into adulthood

49. SLEEP DISORDERS
• REM BEHAVIOR DISORDER (RBD): organized
behavior, from an asleep person
– Begins after age 50
– Followed by symptoms of Parkinson’s disease
– Suggests damage in the brain motor systems

50. SLEEP DISORDERS
• SLEEP-ONSET INSOMNIA: difficulty in falling
asleep
• SLEEP-MAINTENANCE INSOMNIA: difficulty
in staying asleep

51. SLEEP DISORDERS
• SLEEP APNEA: breathing may stop or slow
down when…
– Muscles in the chest and diaphragm relax too
much
– Respiratory neurons in the brainstem don’t signal
properly

52. SLEEP DISORDERS
• SUDDEN INFANT DEATH SYNDROME
(SIDS): sleep apnea resulting from
immature respiratory pacemaker
systems or arousal mechanisms
• Prevention:
– “Back-to-sleep”
– Firm mattress
– No blankets, pillows, stuffed animals

53. SLEEP DISORDERS

54. SLEEP DISORDERS
• Most sleeping pills bind to GABA receptors
throughout the brain.
• Continued use of sleeping pills:
– Makes them ineffective
– Produces changes in sleep patterns that persist
– Can lead to drowsiness and memory gaps

55. SLEEP DISORDERS
SLEEP HYGIENE: controlling behavioral & environmental
factors to enhance sleep
– Behaviors that Interfere with Sleep:
• Napping
• Stimulants
• Eating before sleep

56. SLEEP DISORDERS
SLEEP HYGIENE: controlling behavioral & environmental
factors to enhance sleep