Consciousness: Sleep, Dreams, and Drugs – Psychology Study Notes

Consciousness

Definition and Perspectives

Consciousness refers to our subjective experience of the world, our bodies, and our mental perspectives. It encompasses both waking consciousness and altered states.

• Waking consciousness: Awareness of self and environment during normal wakefulness.

• Altered states of consciousness: Includes sleep paralysis, locked-in syndrome, out-of-body experiences, near-death experiences, mystical experiences, hypnosis, meditation, and psychoactive drug effects.

Sleep Paralysis

Characteristics and Cultural Influences

Sleep paralysis is a phenomenon where an individual is conscious but unable to move, often occurring when waking up or falling asleep, especially during transitions in and out of REM sleep.

• Symptoms: Feeling of being conscious but unable to move, anxiety or terror, sensation of a menacing presence.

• Hallucinations: Intruder, vestibular-motor, and chest pressure hallucinations are common.

• Cultural influences: The content and interpretation of sleep paralysis experiences are shaped by cultural beliefs (e.g., 'Old Hag' in Newfoundland, 'Kanashibari' in Japan, 'Top-hat man' in recent Western culture, 'Pandafeche' in Italy).

Circadian Rhythms

Biological Clock and Regulation

Circadian rhythms are biological cycles that occur over approximately 24 hours, regulating sleep, hunger, concentration, and other physiological processes.

• Suprachiasmatic nucleus (SCN): The brain's clock mechanism, located in the hypothalamus, synchronizes with external light via retinal projections.

• Sleep-wake cycle: Linked to the natural light-dark cycle of the environment.

• Other processes: Body temperature, hormone production, and blood pressure also follow circadian rhythms.

What is Sleep?

Physiological Aspects

Sleep is characterized by low physical activity and a reduced sense of awareness. It is associated with the secretion of several hormones:

• Melatonin: Regulates sleep-wake cycles.

• Follicle stimulating hormone (FSH): Involved in reproductive processes.

• Luteinizing hormone (LH): Also involved in reproduction.

• Growth hormone: Essential for growth and cellular repair.

Stages of Sleep

Sleep Architecture

Sleep occurs in cycles of approximately 90 minutes, consisting of five stages:

• Stages 1-4: NREM (Non-Rapid Eye Movement) Sleep

  • No eye movements, fewer dreams.

  • Stage 1: Transition from wakefulness to sleep (0-15 minutes), brain waves slow down, dreams resemble photos.

  • Stage 2: Further slowing of brain waves, presence of sleep spindles and K-complexes (may help maintain sleep and memory storage), lasts around 20 minutes and comprises up to 65% of total sleep.

  • Stages 3 & 4: Deep sleep, characterized by delta waves, crucial for feeling rested and growth hormone production. Children spend more time in these stages than the elderly. Stage 4 is the hardest to awaken from and is suppressed by alcohol.

• Stage 5: REM (Rapid Eye Movement) Sleep

  • Vivid dreams and quick eye movements.

  • Brain waves similar to wakefulness; paradoxical sleep (brain is active, body is not).

Hypnagogic State

The hypnagogic state is the transitional period before sleep, marked by unique imagery and sensations:

• Hypnagogic imagery: Visual, somatic, and auditory experiences.

• Myoclonic/hypnic jerk: Sudden muscle contractions that may occur during this state.

Summary Table: Stages of Sleep

Stage	Type	Main Features
1	NREM	Transition, slow brain waves, photo-like dreams
2	NREM	Sleep spindles, K-complexes, memory storage
3	NREM	Delta waves, deep sleep, growth hormone
4	NREM	Deepest sleep, hardest to awaken
5	REM	Vivid dreams, rapid eye movement, paradoxical sleep

Additional info:

• Sleep is essential for memory consolidation, learning, and cognitive function.

• Disruptions in sleep (e.g., sleep deprivation, shift work) can have significant effects on mental and physical health.