Key concepts: Characterisitics and Patterns of Sleep

1. Lesson 4: Measuring Physiological Responses
Exam Question:
Ella loves Yoga. She finds it relaxing and it helps her to deal with
the stressful activities of her day.
a) What brainwave pattern would Ella show during a Yoga
session? Explain your response.
b) Which device would best measure Ella’s brainwave pattern?
Explain your response.
Hint: her brainwaves
look similar to this ~>

2. Model Response
a) Alfa waves because Ella is in a meditative state, awake
but very relaxed, which is associated with reasonably
high frequency (but not as high as beta waves) and low
amplitude (but slightly higher than beta waves)
brainwaves.
b) An Electroencephalograph (EEG) because it detects,
amplifies and records electrical activity in the brain in
the form of brainwaves.

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http://www.youtube.com/watch?v=t27suXgfi8w

4. Characteristics of Sleep

5. NREM Sleep Non-rapid eye movement sleep
NREM sleep includes those stages not associated with rapid
eye movements. Adults spend approximately 80 percent of
their nights sleep in NREM, and typically the first half of the
night has more NREM sleep than the second half.
NREM is essential to the physical growth and repair of the
body. Research has found the amount of NREM increases after
vigorous exercise (Vein et al., 1991).
NREM is dream free about 90% of the time, dreams tend to be
more short lived and fragmented than those in REM.

6. NREM Stage 1
~Theta waves, which are of lower frequency and higher amplitude than
alpha waves, appear and start to replace alpha waves.
~Despite the fact that various wave types are shown in this stage, theta
waves define Stage 1 NREM sleep.
~In stage one of sleep, breathing becomes irregular, muscles relax, and
hypnic jerks often occur.
~Stage 1 lasts for approximately 2 min.

7. NREM Stage 2
~In this stage there is a prevalence of theta-wave activity.
~ As sleep deepens EEG recordings begin to pick up unique brain wave
features that are characteristic of stage 2 sleep. Theses include
• Sleep spindles – brief bursts of higher frequency brain waves
• K complexes – single sharp bursts (rise then fall) in amplitude (and
lower frequency).
• Body temperature decreases
~Stage 2 sleep lasts for approximately 20 min

8. NREM Stage 3
~Delta waves begin to appear which are
large and slow.
~Stage 3 is a transitional stage and
lasts for approximately 2 min.

9. NREM Stage 4
~Brain waves become almost pure delta waves
~Regular (slow) heartbeat, slow (rhythmic) respiration &
little muscle activity
~Possible occurrence of night terrors
~Very hard to awaken a sleeper from Stage 4 sleep.

10. REM ~ Rapid Eye Movement
~REM sleep is strongly associated with dreaming. About 85% of the time
a person is awakened from REM sleep they report vivid dreams.
~On average REM sleep totals about 90 min per night. The amount of
REM sleep tends increases with stress in an individuals life.
~REM sleep is sometimes called paradoxical sleep, as aspects of REM sleep
appear to contradict each other. The brain wave pattern is very much like
those produced during alert wakefulness. The bodies internal functioning
is more active during REM sleep than during NREM sleep, the heart beats
faster, breathing is more rapid and irregular, and genitals become
aroused. On the other hand, the sleeper is totally relaxed; most of the
skeletal muscles are totally relaxed (to the point of paralysis).

11. Patterns of Sleep
An adult sleeps for approximately 8 hrs per night progressing through cycles of about 1.5
hours. Periods of deep sleep (NREM4) occur earlier in the night, and periods of REM sleep occur,
on average every 90 minutes.
Adults experience a total of 1-2 hours REM sleep a night, in 4-5 sessions, each progressing in
length.
The period of total REM sleep lessons as individuals get older. A newborn spends approximately
50% of total time in REM sleep compared to an adult who spends approximately 20% of their
time in REM sleep.

12. WHY DO WE SLEEP?

13. Survival Theories
Focuses on when and why different species sleep
Sleep depends on the need to find food
Sleep depends on an animal’s vulnerability to predators
Sleep conserves energy

14. Limitations of Survival Theories
Survival theories fail to explain why we MUST sleep
Survival theories state that sleeping offers security from
predators, however the loss of awareness while asleep
contradicts this statement.

15. Focuses on why sleep is important
The neurotransmitters adenosine
(energy), norepinephrine (alertness)
Immunity to disease
Growth hormones
Restorative Theories Metabolism
Sleep enhances mood
Sleep repairs and replenishes the body and
prepares it for action the next day
Consolidates memories

16. Limitations of Restorative Theories
Lack of physical activity does not reduce the amount
of sleep needed
The body does not completely “rest” during sleep (REM)
as assumed by restorative theories