PSYCHED: SLEEP
Robert Stickgold: led an experiment that found that sleeping after learning a difficult task helps consolidate the learning.
Insomnia: difficulty falling or staying asleep
Sleep apnea: a disorder in which a person stops breathing over a short period of time while asleep
Somnanbulism: when a person rises and walks around while asleep
Narcolepsy: a disorder in which sudden sleep attacks occur in the middle of waking activities
Sleep paralysis: the experience of waking up unable to move
Night terrors: abrupt moments of intense panic and physical arousal
Restless Leg Syndrome: when a person experiences limb movement while asleep
5 Characteristics of dreams: 1. We feel emotions 2. The dream thought is illogical 3. Yet we accept it uncritically 4. We have sensations, especially vision. 5. We don’t usually remember dreams after waking up.
Dreams can include: really specific bits of an experience, an interpretation of a specific sensation felt while sleeping, a repressed thought
Freud: dreams are an expression of the taboo desires of the id, manifest vs latent content, infinite interpretations
Activation-synthesis: dreams are just the brain trying to make sense of neural activity during sleep without access to the external sensory information it would be able to process during wakefulness
Evolved threat rehearsal model: dreams are practice for situations so that we can be ready in real life
Amygdala is active (fear & other emotions), visual association areas responsible for visual imagery (but not visual perception) are active, the prefrontal cortex (involved in planning and executing thoughts) is less active during REM
REM is essential to consolidate learning by transferring info from short to long-term memory. Feedback loop in the hippocampus where short term memory synapses communicate back and forth with the cortex that activated them with sensory information, consolidating the memory.
Consciousness: awareness of ourselves and our environment, mostly associated with language, relates experience created by awareness into a rational scheme.
Awareness: entails a level of perception that can determine behavior and be felt as an experience, lacks language
Freud’s Iceberg : Conscious (thoughts), Preconscious (memories), Unconscious (fears, immoral urges)
No one really knows why we sleep, but we know it’s important
Circadian rhythm: 24 hour biological clock, involves changes in energy/body temp/thinking ability
Ultradian rhythm: more than one peak a day (appetite)
Infradian rhythm: one peak a month (menstruation)
Free-running cycles: biological clocks outside of our control
Entrainment: changing a free-running cycle
Photosensitive ganglion cells: unique cells in retina that directly respond to light, signals pons and pineal gland to stop producing sleep inducing hormones
Suprachiasmatic nuclei: in hypothalamus, series of interconnected cells that receive message sent by PGC, keep time through the use of a complex cycle of gene transcription and protein production that takes approximately 24 hours to complete
Disruption of biological clock: jetlag
To fall asleep: ventrolateral preoptic nucleus sends GABA and galanin (inhibitors) to areas that promote wakefulness (reticular activating system)
Awake - beta waves (high frequency, low amplitude)
Asleep - alpha waves (low frequency, high amplitude)
Beta to alpha = entering stage 1 of sleep: hypnagogic state, slow rolling eye movements involving hypnagogic sensations = hallucinations like falling
Stage 2: theta waves (higher amp than beta but lower frequency), sleep spindles (ictal wavelets) when bursts of rapid, rhythmic brain activity indicative of wakefulness occur but the person does not wake up, K complex which is a sharp burst of brain activity in response to external stimuli
Stage 3 & Stage 4: large, slow delta waves, deep sleep which is the hardest to be woken from (disorientation upon wakening), often combined and called NREM 3
1 - 2 - 3 - 4 - 3 - 2 - 1 then REM sleep/emergent stage 1 sleep = sleep cycle (takes 90 ish minutes)
REM sleep/emergent stage 1 sleep: brain waves go back to acting as if you were awake but you are not, heart rate rises, breathing becomes rapid and irregular, eyes dart around in momentary bursts of activity, genitals also become aroused, motor cortex is very active but its messages are blocked by the brainstem, major muscles are cataplectic (essentially paralyzed from the neck down).
REM is also known as paradoxical sleep because the body is internally quite active but externally asleep.
REM also announces the beginning of dreams. stages 1-4, = fleeting imagery / REM = story-like, emotional, and more bizarre dreams.
Stage 4 gets shorter as the night progresses and eventually disappears. REM and stage 2 get longer as the night progresses.
NREM sleep = all non-REM sleep stages
recent research that shows that dreaming is much more prevalent during NREM than first assumed. REM sleep and dreaming can also be dissociated (ex. by antidepressants or cortical lesions).