Sleep & Consciousness

Sleep & Consciousness 1. a. 2. a. 3. a. 4. a. 1. a. 2. 3. a. 4. a. - States of Consciousness: Consciousness is usually defined as awareness of ourselves and our environment. We can have different states of consciousness/levels of awareness, which can occur naturally or be induced by external factors (i.e. drugs) or internal factors (i.e. our own mental efforts) Alertness is what we typically consider when we are awake and able to interact with others and our environment Beta waves (12-30 Hz) are associated with alertness Daydreaming is where you are awake, but not really aware of the world around you (some people can induce this during light meditation) Alpha waves (8-13 Hz), which disappear in drowsiness but reappear in deep sleep Drowsiness occurs when you are almost asleep but still semi-aware of the world around you (i.e. right before you fall asleep or just as you wake up) → can be induced through deep meditation Theta waves (4-7 Hz) and is also seen right after you fall asleep during “light sleep” Sleep is when you are not aware of yourself nor the world around you Has multiple different wave types and varies depending on what sleep you are in Electroencephologram (EEG) measures your brain waves and they can be typically placed into 4 different categories Sleep Stages & Circadian Rhythms: Each stage of sleep typically occurs in 90 minute cycles during a normal night of sleep, and the first 3 are considering Non-Rapid Eye Movement N1 is the stage between sleep and wakefulness and the brain produces theta waves (similar to drowsiness) Might experience hypnagogic hallucinations which is when you hear or see things that aren’t really there or hypnic jerks which is that feeling of falling N2 is a deeper sleep and is harder to wake someone out of. You will see more theta waves but also sleep spindles and Kcomplexes N3 is also referred to as “slow-wave sleep” with delta waves (0.5-2 Hz) and are very difficult to wake up ( Sleepwalking and sleeptalking occur in this stage Rapid Eye Movement (REM) occurs during the deepest stages of sleep where you muscles are largely paralyzed Also referred to as paradoxical sleep because it seems like your brain is very active but your body is not In a normal night of uninterrupted sleep, you typically cycle through these stages about 4-5 times each The cycle typically goes: N1 → N2 → N3 → N2 → REM → N1 and repeat (90 minute cycle) The length of each stage in the cycle typically varies and depends on things like age Circadian Rhythms tells the body when it is time to go to sleep and often refers to our innate 24-hour biological clock. Can be manipulated with natural or artificial light Dreaming: Dreaming typically occurs during REM sleep (if during Non-REM Sleep, they will typically be less vivid and less memorable) During REM, the brainstem experiences a lot of activity and the frontal cortex has to make sense of it (and often produces dreams) EEG looks like just as if they were awake even though they are sleeping Most dreams last between 5-20 minutes and don’t seem to be localized to any one part of the brain Our pre-frontal cortex is largely inhibited in its normal function during dreams and this is why when you’re in a dream, things make sense but when you wake up you’re like “why the fuck did I think that was normal?” Freud believes that dreams were our unconscious thoughts and desires that needed to be interpreted Evolutionary psychologists believe that dreams serve as threat simulation (in order to practice) and to enhance our problemsolving skills, others even believe dreaming is simply a byproduct of our neural development and serve no real function/purpose Dream Theories Freud, Activation Synthesis Hypothesis: Freud states that dreams are manifestations of our unconscious wishes, thoughts, conflicts, and feelings - Manifest content is what actually happens during the dream (i.e. drowning in an ocean) Latent content is the hidden meaning behind a dream (i.e. drowning from studying for the MCAT for so long) He therefore strongly believed that understanding dreams could help us resolve inner conflict Activation-Synthesis Hypothesis is simply saying that our brains are trying to make meaning and sense of the electrical activity occurring (frontal lobe making sense of electrical activity occurring at the brainstem) → therefore means that our dreams may not truly have any meaning at all - Sleep Disorders: Sleep deprivation can lead to individuals becoming more irritable, poor memory, increase risk of obesity (body produces more cortisol, which is a hormone that tells your body to make more fat, and body produces more of the hormone that tell your body you’re hungry), and even increase your likelihood of developing depression Sleep Disorder Types: Insomnia is when an individual has persistent trouble with falling asleep and staying asleep Narcolepsy is a disorder where an individual cannot avoid falling asleep (affects 1/2000 people) Sleep apnea is a disorder where the individual stops breathing while they’re asleep (affects 1/20 people, so it’s much more common than we may think) Sleep walking/talking occurs during N3 stage of sleep and are mostly genetically linked (usually harmless) → occurs more frequently in children because they experience more N3 sleep than adults do - Breathing Related Sleep Disorders: Apnea simply means that there is an absence of airflow due to some cause (during sleep is termed obstructive sleep apnea where there is some obstruction in the air flow and can manifest as snoring/gasping for air when you sleep) These disorders can lead to individuals feeling tired or sleepy during the day time and feeling unrefreshed in the morning Central sleep apnea occurs when there is an issue with the brain resulting in some breathing problem during sleep Cheyne-Stokes Breathing refers to a crescendo-decrescendo type of breathing during sleep with intermittent periods of no breathing in between (an example of central sleep apnea) Hypoventilation occurs when you are not expelling enough CO2 and it begins to accumulate (can even lead to not getting enough O2)