Consciousness
Consciousness & Sleep
What is consciousness?
Definitions of Consciousness
Useful definition:
is your awareness of everything that is going around you and inside your head at any given moment,
including your thoughts, sensations and feelings, which you use to organise your behaviour
Cognitive Neuroscience
consciousness is generated by a set of action potentials in the communication amongst neurons just
sufficient to produce a specific perception, memory or experience in our awareness
Global Workspace theory
=spotlight of selective attention
The Altered States of Consciousness
→ Consciousness is a spectrum (i.e. levels)
States of consciousness
Waking consciousness
Are animals conscious?
Altered state of consciousness
suppressed consciousness or heightened
Day-dreaming, drugs, meditation, hypnosis
sleep
Your unconscious is making your everyday decisions
Sleep in healthy individuals
Consciousness 1
, Circadian Rhythms
Sleep-wake cycle regulated by Circadian rhythm
Sleep is controlled by the circadian rhythm
The melatonin cycle
Light/no light signal→ SCN (hypothalamus)→pineal gland (secretes melatonin- drug that makes you
sleepy)→ melatonin
Melatonin drugs- given to people who can’t sleep
Influence of blue light screens
Brains can’t detect blue screen lights (from laptops) and normal light
1. The sleep-wake cycle is controlled by an area within the hypothalamus (a section of the brain that influences
the glandular system)
2. The suprachiasmatic nucleus (SCN) (within hypothalamus) – the ‘internal clock’ – is influenced by light
changes. It signals the pineal gland to secrete melatonin. Melatonin makes us feel sleepy.
3. As daylight fades, the SCN signals the pineal gland to secrete melatonin. As melatonin accumulates, one
becomes drowsy.
4. As daylight increases, the SCN signals the pineal gland to stop secreting melatonin and the body awakens.
5. Impact of using light-emitting technology before sleep
Suprachiasmatic Nucleus (SCN)
The Suprachiasmatic Nucleus is situated above the optical chiasma – which is part of the optic nerve
transmitting signals from the eye to the rest of the brain.
In the eyes, light is converted to electrical impulses that travel via the neurons (optical nerve) to the brain
i.e. the significance of its position in relation to it being influenced by light
Why do we sleep?
We spend a considerable amount of our lives in a state of sleep
Sleep is found across species and classes of animals
All mammals
Consciousness 2
, Aquatic animals such as dolphins and fish
Birds
Reptiles
How much sleep?
How much sleep is enough?
Short and long sleepers
Young adults need between
7-9 hours of sleep per night
Decreases as one ages
Guidelines
Sleep in Healthy Individuals
Sleep is comprised of NREM and REM sleep
REM (Rapid Eye Movement)
Active type of sleep
Most dreaming
Voluntary muscles are inhibited
NREM (Non-Rapid Eye Movement) Sleep
Deeper
More restful
Free to move around
3 stages of NREM
N1-N3 (used to be N1-N4)
combined N3 and N4 so there is only N1, N2 and N3
N1= light sleep
Brain wave activity slows down
Some dreaming (hallucinations)
Consciousness 3
Consciousness & Sleep
What is consciousness?
Definitions of Consciousness
Useful definition:
is your awareness of everything that is going around you and inside your head at any given moment,
including your thoughts, sensations and feelings, which you use to organise your behaviour
Cognitive Neuroscience
consciousness is generated by a set of action potentials in the communication amongst neurons just
sufficient to produce a specific perception, memory or experience in our awareness
Global Workspace theory
=spotlight of selective attention
The Altered States of Consciousness
→ Consciousness is a spectrum (i.e. levels)
States of consciousness
Waking consciousness
Are animals conscious?
Altered state of consciousness
suppressed consciousness or heightened
Day-dreaming, drugs, meditation, hypnosis
sleep
Your unconscious is making your everyday decisions
Sleep in healthy individuals
Consciousness 1
, Circadian Rhythms
Sleep-wake cycle regulated by Circadian rhythm
Sleep is controlled by the circadian rhythm
The melatonin cycle
Light/no light signal→ SCN (hypothalamus)→pineal gland (secretes melatonin- drug that makes you
sleepy)→ melatonin
Melatonin drugs- given to people who can’t sleep
Influence of blue light screens
Brains can’t detect blue screen lights (from laptops) and normal light
1. The sleep-wake cycle is controlled by an area within the hypothalamus (a section of the brain that influences
the glandular system)
2. The suprachiasmatic nucleus (SCN) (within hypothalamus) – the ‘internal clock’ – is influenced by light
changes. It signals the pineal gland to secrete melatonin. Melatonin makes us feel sleepy.
3. As daylight fades, the SCN signals the pineal gland to secrete melatonin. As melatonin accumulates, one
becomes drowsy.
4. As daylight increases, the SCN signals the pineal gland to stop secreting melatonin and the body awakens.
5. Impact of using light-emitting technology before sleep
Suprachiasmatic Nucleus (SCN)
The Suprachiasmatic Nucleus is situated above the optical chiasma – which is part of the optic nerve
transmitting signals from the eye to the rest of the brain.
In the eyes, light is converted to electrical impulses that travel via the neurons (optical nerve) to the brain
i.e. the significance of its position in relation to it being influenced by light
Why do we sleep?
We spend a considerable amount of our lives in a state of sleep
Sleep is found across species and classes of animals
All mammals
Consciousness 2
, Aquatic animals such as dolphins and fish
Birds
Reptiles
How much sleep?
How much sleep is enough?
Short and long sleepers
Young adults need between
7-9 hours of sleep per night
Decreases as one ages
Guidelines
Sleep in Healthy Individuals
Sleep is comprised of NREM and REM sleep
REM (Rapid Eye Movement)
Active type of sleep
Most dreaming
Voluntary muscles are inhibited
NREM (Non-Rapid Eye Movement) Sleep
Deeper
More restful
Free to move around
3 stages of NREM
N1-N3 (used to be N1-N4)
combined N3 and N4 so there is only N1, N2 and N3
N1= light sleep
Brain wave activity slows down
Some dreaming (hallucinations)
Consciousness 3
