Circadian rhythms regulate the body's sleep-wake cycle over 24 hours, with alertness peaking around noon and 6pm and dipping around 3am. The hypothalamus influences glands like the pineal gland to secrete melatonin and induce sleepiness according to our internal biological clocks. There are two main theories for why we sleep: the adaptive theory proposes sleep evolved to avoid nocturnal predators, and the restorative theory suggests sleep is necessary to physically replenish our bodies and repair cellular damage during rest.

1. Consciousness & Sleep
Day 1 Notes

2. Awareness
of
everything
going
on
within
ourselves
and our
surroundings
onsciousness

3. FREUD’S THEORY OF CONSCIOUSNESS
3
# 1
# 2
# 3
Hold up the
number of fingers
(1, 2, or 3) which
best represents
the preconscious
mind.

4. BODILY RHYTHMS
Circadian Rhythm
– A biological rhythm of Sleep, Alertness, and Body
Temperature changes
– 24 Hour sleep/wake cycle
– Alertness slowly increases until around noon and then decreases until a dip around 3pm,
rises and peaks again around 6pm, then decreases slowly until around 3am and then
gradually increases throughout the morning.
Rhythms:
– Jet lag can mess with rhythms
– Bright light can reset our natural
“clock”
4
Did you know?
If all light cues and clocks are hidden,
we will adapt to a 25-hour day

5. Necessity of Sleep
• Circadian rhythm
– 24 hour bodily
rhythm
• Hypothalamus –
tiny section of
brain influences
glandular system
• Suprachiasmatic
nucleus –internal
clock tells people
wake up/fall
asleep
• tells pineal gland
secrete melatonin
for sleepiness
4.2 Why do people need to sleep and how does it work?

6. Theories of WHY We Sleep
• Animals evolved sleep patterns to avoid predators by
sleeping when predators are most active
Adaptive theory - theory of sleep proposing that animals
and humans evolved sleep patterns to avoid predators by
sleeping when predators are most active.
Restorative theory - theory of sleep proposing that sleep is
necessary to the physical health of the body and serves to
replenish chemicals and repair cellular damage.