6 sleep

Question 1

theories about REM sleep

Answer 1

3 hypothesis: Memory Theory 1) that rem is important for memory storage and discards useless info from the day

2nd : Eye Theory move our eyes to supply oxygen to the corneas
Criticism: not enough evidence for either of these. Need more data

3) Another hypothetical theory about rem: This is our default setting so its difficult to stay in non-rem sleep, so brain switches back to REM sleep. This is quite debatable
This would explain REM getting longer throughout the night, because brain wants to get back to that REM “Default setting”

Question 2

theories of sleep: recuperative theories

Answer 2

being awake disrupts the homeostasis, so the sleep is required for restoration.
Criticism: doesn’t depend on the activities of the day, using a lot of physical/mental activity doesn’t necessarily mean you’ll sleep more

Question 3

theories of sleep: Adaptation/evolutionary theory:

Answer 3

Adaptation/evolutionary theory: sleep to conserve energy when the environment is hostile (night is dangerous, and you need to conserve energy for the day)
Criticism: if sleep wasn’t crucial, it would have “died out” through evolution

Question 4

theories of sleep: memory consolidation theory

Answer 4

you go over the processes and information absorbed in the day so brain can store the important issues and discard the unimportant.
Criticism: when you have sleep REM deprivation you don’t have memory issues

Question 5

sleep deprivation consequences

Answer 5

concentration loss (less ability for cognitive functions), memory impairment, health (blood pressure, immune system), and mood (negative effect)

Consequences of not having REM sleep: irritability, personality changes, increased eating, increased anxiety, impaired concentration

Question 6

stages of sleep

Answer 6

Wakeful state: amplitudes are smaller, more frequent, not very synchronized
More relaxed state: frequency lowers, amplitude increases
Stage 1: high freq and low amplitude, mostly irregular, low voltage
With increasing sleep, brain activity drops, heart rate and metabolic activity slows down
Stage 2: sleep spindles and k-complexes (larger waves with sharp increase/decrease)
Stage 3 and 4: Slow wave sleep: larger waves and more synchronized
After you progress through the stages, you return back through the stages in reverse order. Once you reach stage 1, “emergent stage 1 sleep”, is called REM sleep. In this stage, your muscles are relaxed and not much movement, (reason for less movement is to help us not act out our dreams)
Initial stage 1 EEG: (when you first fall asleep): cant see many changes in the EEG, no REM sleep in this stage
Emergent stage 1: REM EEG: much more noticeable in the EEG changes.
*Stages go like this: stage 1, 2, 3, 4, then cycle back 3, 2, 1(and this is when REM occurs), back to 2,3,4, etc.
*How REM sleep changes during the night: when deprived of REM, when they were able to sleep again they had signif Longer REM sleep. As you go through the cycles, the time in REM stage increases

Question 7

Brain areas involved in sleeping: posterior hypothalamus and anterior hypothalamus

Answer 7

Posterior hypothalamus - promotes wakefulness
​​Anterior hypothalamus - promotes sleep

Question 8

Brain areas involved in sleeping: locus coeruleus

Answer 8

stimulation of this strengthens storage of recent memories, inactive during sleep. Effect: responsible for wakefulness and alertness but activates in response to meaningful events. In REM it is inactive. So how does this affect your dreams? We don’t remember our dreams because this structure is inactive, and within the dream the plot changes easily and readily because you forget what you were just doing (explaining the chaos of plots in dreams.)

Question 9

Brain areas involved in sleeping: Reticular formation activation

Answer 9

Reticular formation activation - involved in arousal, regulates arousal, responsible for sleep and wake transaction

Question 10

Brain areas involved in sleeping: pineal gland and suprachiasmatic nucleus

Question 11

brain areas involved in sleeping: Bmal1 and cryptochrome

Answer 11

2 proteins: clock and Bmal1 promote gene expression of period (per) and cryptochrome (cry), then they inhibit clock and Bmal1. Period and cryptochrome start to break down. Once they break down, Clock and BMAL1 reset the cycle. About a 24-hour cycle.

Question 12

Is there a difference between sleeping through the night and taking naps during the day?

Answer 12

Naps dont have the REM sleep, you dont go through the stages as often, the quality of sleep changes, having the consecutive hours helps for the REM sleep activation. If you do take naps during the day, must be on schedule as to not mess up overall rhythm.
Leonardo davinci sleeping 15 minutes every 2 hours: this schedule can work for people that may need it (solo sailing trips, marathons, anything repairing a specific sleep pattern) One controversial point is some* argue that this is actually more effective than the longer sleep cycle.

Question 13

dreams: Freudian theory
Activation-synthesis hypothesis
Clinic-anatomical hypothesis

Question 14

neurotransmitters involved in sleep: GABA

Answer 14

inhibits the thalamus and cortex, inhibits the synaptic activity of the brain, so therefore increase in GABA release produces sleep. (specifically for nonREM sleep) In REM sleep, there’s cholinergic activity (excitatory effects.)

Question 15

neurotransmitters involved in sleep: acetylcholine

Answer 15

increases learning and retention. Shifts sleep from non rem sleep to rem sleep. (Excitatory)

Question 16

neurotransmitters involved in sleep: orexin

Answer 16

controls arousal and excitatory in all areas of the brain

Question 17

neurotransmitters involved in sleep: histamine

Answer 17

increases arousal (anti-histamines are used and drowsiness occurs) it’s connected to the posterior part of hypothalamus. Histaminergic system is exclusively located there

Question 18

neurotransmitters involved in sleep: serotonin

Answer 18

not active during REM sleep so if active it interrupts REM sleep, project wakefulness.

Question 19

Neurotransmitter involved in sleep: norepinephrine

Answer 19

for wakefulness and not active in REM sleep

Question 20

circadian rhythms

Answer 20

Duration of rhythm: is based on light. retina in eyes detect sunlight and sends signal to SCN to release cortisol and create waking signals, also setting the clock for melatonin to be released at night. **tracts go from retina to SCN just above optic chiasm, this is known as retinohypothalamic pathways. SCN also communicates to pineal gland about melatonin. And melatonin gives feedback to SCN to reset the internal clock. Temporal cues are based on light.
Body temperature also changes throughout the day according to this rhythm rising through day, with peak around 4-6PM, and then back down
Extracting SCN from rats led to action potentials still being produced according to circadian rhythm, and when put into other rats, the donor’s rhythm impacted the receiving rat.

Question 21

Activation synthesis hypothesis:

Answer 21

your brain is making sense of all incoming information, and the dream is “making sense of it all”. Focus is on the pons and PGO waves which stimulates the amygdala (portion of temporal lobe) and is important in processing emotions. Giving reason for dreams having high emotional content.
Criticism: doesn’t always happen that you always dream of falling although you are laying down
Even with damaged pons you still dream

Question 22

Clinico Anatomical Hypothesis

Answer 22

not getting information from the senses so t can generate images without constraint. Dreams are cognition and just “thinking.” the primary motor cortex and spinal cord neurons are suppressed so you don’t move
Stimuli in brain combined with recent memories and any info from current senses (like if you hear a cry, it could be in your dream.)