Ch.5 Flashcards
Circadian rhythm
Cyclical changes that occur on a roughly 24-hour basis in many biological processes. Also known as the brains biological clock. The term for the suprachiasmatic nucleus (SCN) in the hypothalamus that’s responsible for controlling our level of alertness. The urge to snooze comes over us at night as well because the level of the hormone melatonin, which triggers feelings of sleepiness, increase after dark. The biological clock is pervasive in nature and ticks even the lowliest forms of life, including marine algae, bacteria, and red blood cells, too.
Sleep deprivation
Because the need for sleep varies, a good rule of thumb for the right amount of sleep is if you feel rested during the daytime and don’t feel fatigued and need to nap the next day. Ordinarily, there don’t seem too many negative consequences for losing one nights sleep other than feeling edgy, irritable, and unable to concentrate well the next day, which could increase the risk of driving accidents. Yet after a few nights of sleep deprivation, we feel more “out of it” and begin to accumulate a balance of “sleep debt,” which can require at least several nights of sleeping a few extra hours to pay off. After more than four days of severe sleep deprivation, we may experience brief hallucination such as hearing voices, or seeing things.
Rapid eye movement (REM) 
Darting of the eyes underneath closed eyelids during sleep. Where vivid dreams occurs, usually. REM is turned on by surges of the neural transmitter acetylcholine, as the neurotransmitters Serotonin and norepinephrine are shut down. Acetylcholine activates nerve cells in the pons, while Dwindling levels of serotonin and norepinephrine decrease reflective thought, reasoning, attention, and memory. The activated pons sends incomplete signals to the lateral geniculate nucleus of the thalamus, a relay for sensory information to the language and visual areas of the forebrain. This is the activation part of the activation- synthesis theory. The forebrain does it’s best to cobble together the signals it receives into a meaningful story. That’s the synthesis part of the theory. The amygdala is also ramped up adding the emotional colours of fear, anxiety, anger, sadness, and elation to the mix. 
Non-REM (NREM) sleep
Stage 1 through 4 of the sleep cycle, during which rapid eye movement do not occur and dreaming is less frequent and vivid. During sleep we repeatedly passed through five stages every night. Each cycle lasts about 90 minutes, and each stage of sleep is clearly distinguishable from awaken states.
Stage 1 sleep
In this light stage of sleep, which lasts for 5 to 10 minutes, our brain activity powers down by 50% or more producing theta waves, which occur 4 to 7 times per second. These waves are slower than beta waves of 13 or more times per second produced during active alert states and the alpha waves of 8 to 12 times per second one we are quiet and relaxed. As we drift off into deeper sleep, we become more relaxed and we may experience hypnagogic imagery—scrambled, bizarre, and dream-like images that flit in an out of consciousness. We may also experience sudden jerks (sometimes called myoclonic jerks) of our limbs as it being startled or falling. 
Stage 2 sleep
In stage 2 sleep our brain waves slow down even more. Sudden intense bursts of electrical activity called sleep spindles of about 12 to 14 cycles per second, and occasionally sharp rising and falling waves known as K-complexes, First appear in the EEG. K-complexes appear only when we were asleep. As our brain activity decelerates, our heart rate slows, our body temperature decreases, our muscles relax even more, and our eye movements cease. We spend as much as 65% of our sleep in stage 2. 
Stages 3 and 4 sleep
After about 10 to 30 minutes, light sleep gives way too much deeper slow-wave sleep, in which we can observe delta waves, which are as slow as 1 to 2 Cycles per second in the EEG. In stage 3, delta waves appear 20 to 50% of the time in stage 4 they appear more than half the time. More recently, researchers have tended to conceptualize sleep stages 3 and 4 in terms of a single, consolidated state of sleep, marked by slow-wave, deep sleep. To feel fully rested in the morning, we need to experiences these deeper stages of sleep throughout the night. 
Stage 5 sleep
(REM sleep) After 15 to 30 minutes, we return to stage 2 before a brain shift dramatically into high gear, with high frequency, low-amplitude waves resembling those of wakefulness. Commonly known as REM sleep- Stage asleep during which the brain is most active and vivid dream in most often occurs. Occupies about 20 to 25% of our night’s sleep. After about 10 to 20 minutes of REM sleep, the cycle starts up again as we glide back to the early stages of REM sleep and then back into deeper sleep yet again. Each night we cycle back to REM sleep 5 or 6 times.
REM and non-REM dreams
Many REM dreams are emotional, illogical, and prone to sudden shifts in “plot.” In contrast, non-REM dreams are often shorter, are more thought-like and repetitive, and deal with every day topics of current concern to us like homework, shopping lists, or taxes. During REM is a phenomenon called middle ear muscle activity, in which the muscles of our middle ear become active, almost as though they’re assisting us to hear sounds in the dream.
Lucid dreaming
Experience of becoming aware of that one is dreaming. Experiencing lucid dream parts of the cerebral cortex associated with self perception and evaluating thoughts and feelings wrap up with activity. 
Insomnia
Difficulty falling and staying asleep.
(A) Having trouble falling asleep (Regularly taking more than 30 minutes to doze off).
(B) Waking too early in the morning
(C) Waking up during the night and having trouble returning to sleep. 
Long-standing use of many sleeping pills can create dependency and make it more difficult to sleep once people stop taking them phenomenon called rebound insomnia. 
Narcolepsy
Disorder characterized by the rapid it often unexpected onset of sleep. Surprise, elation, or other strong emotions— even those associated with laughing at a joke or engaging in sexual intercourse can lead some people with narcolepsy to experience cataplexy, a complete loss of muscle tone. During cataplexy people can fall because their muscles become limp as a ragdoll.  cataplexy occurs in healthy people during REM sleep but in narcolepsy people experiencing cataplexy remain alert the whole time even though they can’t move. The hormone orexin plays a key role in triggering sudden attacks of sleepiness.
Sleep apnea
Disorder caused by the blockage of airway during sleep resulting in multiple awakenings during the night and daytime fatigue
Night terrors
Sudden waking episodes characterized by screaming, perspiring, and confusion followed by returned a deep sleep. 
Sleepwalking
Walking while fully asleep. May be somewhat clumsier. Almost always occurs during non-REM (Especially stage 3 or 4) sleep
Freud’s Dream protection theory
Describes dreams as the guardians (Protectors) of sleep. During sleep, the ego which acts as a sort of mental censor, is less able than when awake to keep sexual and aggressive instincts at bay by repressing them. If not for dreams this instance with bubble up disturbing sleep. The dream-work disguises in contains the pesky sexual and aggressive impulses by transforming them into symbols that represent wish-fulfilment—how we wish things could be. Dreams don’t surrender their secrets easily— they require interpretation to reverse the dream-work and reveal their true meaning. He distinguished between the details of the dream itself, which he called the manifest contact, and it’s true, hidden meaning, which he called the Latent context. If, as Freud claimed, “wish fulfillment” is the meaning of each and every dream, we’d expect dream content to be mostly positive. but it’s not.
Activation synthesis theory 
Theory that dreams reflect inputs from brain activation originating in the pons, which the forebrain then attempts to weave into a story. Maintain that dreams reflect the activated brain’s attempt to make sense of random and internally generated neural signals during REM sleep. 
Neurocognitive Theory
Theory that dreams are supported by the brain’s default Network and are a meaningful product of our cognitive capabilities, which shape what we dream about. According to Domhoff, dreams are simulations in which we imaginatively place ourselves in different mental scenarios and explore possible outcomes. 
Dream continuity hypothesis
Hypothesis that there is continuity between sleeping and waking experiences and that dreams can mirror life circumstances. 
Hallucinations
Realistic Perceptual experiences in the absence of any external stimuli and they can occur in any sensory modality. Brain scans reveal that when people report visual hallucinations, their visual cortex becomes active, just as it does when they see a real object. The same correspondence holds true for other senses, like hearing and touch, underscoring the link between our perceptual experiences and brain activity. 
Out-of-body experience (OBE)
Sense of our consciousness leaving our body. Research suggests the when our senses of touch and vision are scrambled the result is a disruption of our experience of our physical body with striking resemblance to an OBE. The drug ketamine, Which users often report produces bizarre out-of-body experiences and feelings of detachment from the physical world, disrupts the patterns of brain activity that bring about a unified sense of self and body by reducing transmission of the neurotransmitter glutamate.
Near death experiences (NDFs)
Out-of-body experience reported by people who’ve nearly died or thought they were going to die. NDEs differ across people and cultures, suggesting they don’t provide a genuine glimpse of the afterlife but are constructed from prevalent beliefs about the hereafter in response to the threat of death.
Scientist have offered alternative explanations for NDEs based on changes in chemistry of the brain associated with cardiac arrest, Anaesthesia, and other physical trauma’s. For example, a feeling of complete peace that can accompany an NDE may result from the massive release of endorphins in the dying brain, and buzzing, ringing, or other unusual sounds maybe the rumblings of an oxygen-starved brain. Researchers suggest that cascades of neurotransmitters might account for NDEs because the neurotransmitters that shot up before death are associated with changes in alertness, attention, and arousal (norepinephrine); cognitive and emotional experiences (dopamine); and visual hallucinations and mystical experiences (Serotonin).
