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 various 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 effects of psychoactive drugs.

Sleep Paralysis

Characteristics and Cultural Influences

Sleep paralysis is an altered state of consciousness occurring when waking up or falling asleep, often during transitions into or out of REM sleep.

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

• Hallucinations: Intruder, vestibular-motor, or chest pressure hallucinations.

• Cultural influences: Cultural beliefs shape the content and interpretation of sleep paralysis experiences (e.g., 'Old Hag' in Newfoundland, 'Kanashibari' in Japan, 'Top-hat man' in recent Western reports).

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 environmental light via retinal projections.

• Sleep-wake cycle: Linked to natural light-dark cycles; body temperature, hormone production, and blood pressure follow circadian rhythms.

What is Sleep?

Physiological Features and Hormonal Secretion

Sleep is a state of low physical activity and reduced awareness, essential for health and well-being.

• Hormones secreted during sleep:

  • Melatonin

  • Follicle stimulating hormone (FSH)

  • Luteinizing hormone (LH)

  • Growth hormone

Stages of Sleep

Sleep Architecture and Brain Activity

Sleep occurs in cycles of approximately 90 minutes, consisting of five stages. These stages are divided into NREM (Non-Rapid Eye Movement) and REM (Rapid Eye Movement) sleep.

• Stages 1–4: NREM Sleep

  • No eye movements, fewer dreams.

  • Stage 1: Transition from wakefulness to sleep (0–15 minutes), slowing brain waves, brief dream-like images.

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

  • Stages 3 and 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 Sleep

  • Vivid dreams and rapid eye movements.

  • Brain waves resemble wakefulness (paradoxical sleep).

  • Body is paralyzed except for inner ear movements.

Hypnagogic State

Pre-Sleep Consciousness

The hypnagogic state is the transitional phase between wakefulness and sleep, often accompanied by vivid sensory experiences.

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

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

Summary Table: Stages of Sleep

Stage	Type	Key Features
Stage 1	NREM	Transition, slowed brain waves, brief imagery
Stage 2	NREM	Sleep spindles, K-complexes, memory support
Stage 3	NREM	Delta waves, deep sleep, growth hormone
Stage 4	NREM	Deepest sleep, hardest to awaken
Stage 5	REM	Vivid dreams, rapid eye movement, body paralysis

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.