1. Body Rhythms & Sleep

2. Biological Rhythms
Natural variations we experience daily in our psychological and physiological functioning
Fall into three main categories
Circadian Rhythms
Ultradian Rhythms
Infradian Rhythms

3. Circadian Rhythms
Any rhythmic change that occurs approximately once in a 24-hour cycle
Responsible for our arousal levels throughout the day.
Many of your processes like blood pressure, hormones, pain sensitivity along with sleep and wake cycles vary over the day
If time, watch the Cave Experiment from The Brain: Module 13 (6 min)
In the absence of time cues, the cycle period will become somewhat longer than 24 hours

4. Hockenbury text p 124

5. The Body’s Clock
Suprachiasmatic nucleus (SCN) — cluster of neurons in the hypothalamus that governs the timing of circadian rhythms
Melatonin —hormone of the pineal gland that produces sleepiness

6. The Body’s Clock: How it works
Special photoreceptors in the retina regulate the effects of light on the body’s circadian rhythms
In response to morning light, signals from these special photoreceptors are relayed via the optic nerve to the suprachiasmatic nucleus.
In turn, the suprachiasmatic nucleus causes the pineal gland to reduce the production of melatonin, a hormone that causes sleepiness.
As blood levels of melatonin decrease, mental alertness increases.
Daily exposure to bright light, especially sunlight, helps keep the body’s circadian rhythms synchronized and operating on a 24-hour schedule.

7. How Melatonin works:
More melatonin = sleepy and reduce activity levels
highest levels between 1-3 AM
Less Melatonin = more alert and active
Body stops produced melatonin shortly before sunrise and sunlight suppresses melatonin levels throughout the day
Jet Lag – Since your body is still operating on the time you left from, your melatonin levels will be off causing a disruption in your circadian rhythms and making you mentally fatigued, depressed, irritable and have problems sleeping.
Night workers will always have some problems due to sunlight resetting their biological clock.

9. Biological Rhythms
Play “Can You Beat Jet Lag?” (6:44) - (Start at 16:00).
Segment #15 from Scientific American Frontiers: Video Collection for Introductory Psychology (2nd edition)
How light is used by the body to “reset” your biological clock.

10. Not a Morning Person?
Sleep Inertia - feeling of grogginess or impaired mental ability immediately following an abrupt awakening
Staying in bed until the last possible moment will only intensify disorientation as you hustle to work.
Best way to treat it is to allow for more passage of time.
Set your alarm 15 minutes earlier and make it so you have to get up to turn it off.
Drink something with caffeine and sit near sunlight.
Read something or do meditation to get your brain engaged.

11. Ultradian Rhythms
Biological rhythms that occur more than once each day
Example: Cycling through the stages of sleep throughout the night, appetite

12. Infradian Rhythms
Biological rhythms that occur once a month or once a season
These rhythms are infrequent
Example:
Women’s menstrual cycle
bear’s winter hibernation

13. The Stages of Sleep

14. Why do We Sleep?
Restoration theory—body wears out during the day and sleep is necessary to put it back in shape
NREM sleep sees increases in the release of growth hormone, testosterone, prolactin.
REM sleep plays a role in rate of brain development that occurs in the early stages of the lifespan.
Allows neurons to repair themselves while pruning unused connections
Sleep consolidates memories – strengthening neural connections
Allows us to be better problem solvers the next day
Adaptive theory—sleep emerged in evolution to preserve energy and protect during the time of day when there is little value and considerable danger
Animals with few natural predators sleep the most while animals with many sleep less.
Hibernation occurs during the time of year most hazardous to the animal.
Keywords: restoration theory, preservation and protection theory

15. Electroencephalograph (EEG)
A machine that amplifies and records waves of electrical activity that sweep across the brain’s surface
Electrodes are placed on the person’s scalp to measure the waves
Used as a means to measure the stages of sleep

16. Electroencephalogram (EEG)
Discovering Psych Schulman Slides
Keywords: electroencephalogram, EEG
Electrodes placed on the scalp provide a record of the electrical activity of the brain
EEG recordings are a rough index of psychological states

17. EEG Waves of Wakefulness
Beta Waves:
Awake & attentive
low amplitude
fast, irregular
Discovering Psych Schulman Slides
Keywords: EEG, alpha waves, beta waves, wakefulness
Alpha Waves:
Awake but non-attentive
Larger amplitude

18. Onset of Sleep
Awake & alert, your brain produces small, fast brain waves called beta waves.
As you lay down and close your eyes, your brain's electrical activity gradually gears down generating slightly larger and slower alpha brain waves.
During drowsy, presleep stage you may experience vivid sensory phenomena called hypnagogic hallucinations.
Most common hallucination is that of falling which can produce a myoclonic jerk or sleep starts – involuntary muscle spasm of the whole body that jolts the person completely awake.

19. Stage 1 Sleep Breathing is slowed. Brain waves become irregular.
It is easy to wake the person, who will insist they are not asleep.
Lasts only a few minutes.
Familiar sounds fade away but your can regain alertness if something interrupts you.
Some imagery is common although no very strange or vivid.

20. Stages of Sleep

21. Stage 1

22. Stage 1

23. Stage 2 Sleep Brain wave cycle slows.
Appearance of sleep spindles or brief bursts of brain activity and K complexes or large high-voltage spikes of brain activity that periodically occur.
Brain activity slows considerably and breathing becomes rhythmic.
Slight muscle twitches occur.
Brain waves begin to slowly switch from Theta waves to slower and larger delta waves.

24. Stage 2
K Complex

25. Stages 3 and 4 Sleep “Slow Wave Sleep”
Increase in delta waves (large & slow waves per second)
20% = Stage 3. More than 50% = Stage 4.
First time through stage 4 is about 30 minutes and is where one gets rejuvenated
During the first stage 4 of sleep, heart rate, blood pressure and breathing drop to their lowest levels and it is very hard to wake up.
Sleepwalking occurs here.
People can "wake up" during stage 4 and do a simple task and not remember it.

26. Stage 4

27. Stages of Sleep1-4 Quick Review
Sleep stage 1: brief transition stage when first falling asleep
Stages 2 through 4 (slow-wave sleep): successively deeper stages of sleep
Slow Wave 3 & 4: Characterized by an increasing percentage of slow, irregular, high-amplitude delta waves
Delta waves
Sleep stage 1
1 second
Sleep stage 4
Sleep stage 2
Spindlers (bursts of activity)
Discovering Psych Schulman Slides
Keywords: sleep stage 1, sleep stage 2, sleep stage 3, sleep stage 4, delta waves

28. REM Sleep N-REM (non-REM sleep) = Stages 1 - 4
REM Sleep - Rapid eye movement as eyes move quickly back and forth
Most dreaming occurs in REM
muscle activity is suppressed to keep you acting them out.
REM Rebound - If denied REM sleep and then allowed a person will “Catch Up” on REM sleep and will increase their time in REM by 50%.

29. REM Sleep

30. REM: Paradoxical Sleep
One’s physiology is close to that of being awake but the brainstem blocks all muscle movement
Brain wave patterns are similar to when a person is awake
Visual and motor neurons in the brain fire like they do when you are awake.
Eyes dart back and forth and heart rate, blood pressure and respirations fluctuate up and down.
The first REM cycle lasts for 5 to 15 minutes. Each one gets longer as night goes on.

31. Stages of Sleep
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
Keywords: REM sleep, sleep cycles

32. Typical Night’s Sleep

33. DiscPSY Figure 4.2 p. 132

34. Sleep Changes through Life

35. Sleep Review Play “Sleep: Brain Functions” (11:12)
Module #14 from The Brain: Teaching Modules (2nd edition).
Review of the stages of sleep.
What happens to animals that are not allowed to sleep?
What defines normal & abnormal sleep?
Categories of Sleep Disorders