Lecture 11 Flashcards
Sleep research is conducted where
in a sleep laboratory.
Electrodes placed around the eyes monitor eye movements recorded aswhat
an electro- oculogram (EOG).
Electrodes are also attached to the subjects chin to record muscle activity recorded as what
an electromyogram (EMG).
Electrodes are attached to the subjects scalp to record electrical activity of the brain. The amplifier records a what
electroencephalogram (EEG).
what are the stages of sleep
awake REM non-rem stage 1 non-rem stage 2 non-rem stage 3 (formerly stage 3&4)
what is the characteristics with regard to the wavelengths during stage 4 vs awake
stage 4– low frequency, high amplitudes
awake– low amplitudes, high frequency
what is Slow-wave sleep
sleep stages 3- 4; deep, non-REM sleep; associated with large amplitude, low frequency oscillations of brain activity as measured with EEG. This pattern of neural activity reflects bursts of action potentials that are synchronized across large collections of neurons.
what is Rapid eye movement (REM) sleep
also called paradoxical sleep: desynchronized EEG activity, rapid eye movements, and muscle paralysis; associated with dreaming; apart from occasional twitching, muscles are totally inactive. Cerebral blood flow and oxygen consumption increase.
what are the EEG SIGNALS DURING SLEEP
beta activity
alpha activity
theta activity
delta activity
what is Beta activity,
13–30 Hz; typical of an aroused state. It reflects desynchronous neural activity (high frequency, low amplitude oscillations)
what is Alpha activity,
8–12 Hz; typical of awake person in a state of relaxation
what is Theta activity,
3.5–7.5 Hz; appears intermittently when people are drowsy, and is prominent during early stages of slow-wave sleep
what is Delta activity;
<4 Hz; occurs during deepest stages of slow-wave sleep; reflects synchronized low frequency, large amplitude brain activity
Starting after about 10 minutes of sleep, EEG recordings of humans include a mixture of what
sleep spindles and K complexes.
what are Sleep spindles
short bursts of desynchronized activity (12-14 Hz) which occur between 2-5 times a minute during sleep stages 1-4.
what are K complexes
sudden, sharp waveforms. They are technically only found during stage 2 sleep, but they resemble the delta waves prominent during deeper stages of sleep. They occur spontaneously at approximately 1 per minute and can be triggered by unexpected noise. Older people often have more K complexes.
what happens to muscles in REM sleep
they go limp
If you don’t sleep what happens
You feel tired, but generally, physically, your body is fine. Your mind however beings to deteriorate. You start to exhibit delayed reaction times and poor judgment (as measured on performance in cognitive tests).
• You have increases in stress hormones, mood swings, and impulsive behavior.
• You exhibit worse learning and memory.
• You increase your propensity for weight gain, migraines, hallucinations, dementia, seizures, and death.
• A sleep debt is created that must be repaid (in most species).
• Microsleep states often appear, where animals fall asleep for brief episodes lasting several seconds, during which time they are perceptually ‘blind‘ and often unaware that they have fallen asleep.
• Sleep disruptions often precede and exacerbate mental illnesses
can lack of sleep cause death
yes
how do Dolphin sleep
highlights an especially remarkable solution to the problem of maintaining vigilance during sleep. Their version of sleep alternates between the two cerebral hemispheres
aka each hemisphere sleeps separately
do all animals sleep
it appears so
give an example of large developmental differences within species
50% of human infant sleep is REM sleep
• 25% of human adult sleep is REM sleep
There are even larger differences between species in what sense
Amount of sleep
• Ratio of REM to non-REM sleep
• Length of sleep cycles (average time between two REM events)
As a general rule, predatory animals indulge in long, uninterrupted periods of sleep.
Animals that are preyed upon typically sleep during short intervals that may last no more than a few minutes.
what is the correlations between sleep and body weight
The amount of time a species sleeps each day is inversely correlated with weight
the smaller the animal, the more they seep and rise versa
what is the correlation between metabolic rate and body weight
While overall metabolic rate increases as mass increases, metabolic rate per pound (or per cell) decreases as mass increases.
what is the correlation between metabolic rate and sleep
↑ body mass, ↑ brain mass, ↑ overall metabolic rate but ↓ metabolic rate per kg (or per cell), ↓ heart rate, ↑ life span, ↓ total sleep time, ↑ length of sleep cycles
• For example, large animals have low metabolic rates per cell and long life spans. They don’t sleep very much, but each sleep session is relatively long.
• Why do all these correlations exist?
- One hypothesis is that it all has to do economies of scale related to nutrient and waste distribution networks. Large animals benefit from economies of scale (i.e. heat savings and more efficient distribution networks), so each cell doesn’t have to work as hard.
- The fact that total sleep time is highly correlated with all of these variables suggests that sleep may be critical for restorative process
what are the main theories of why animals sleep
energy conservation
brain processing
restoration of some kind
explain the energy conservation theory
Ifyouusuallyspendthenightsittingquietlyhidingina cave, you might as well be sleeping and conserving energy.
Part of this theory is that sleep is a time for “serious” rest, a respite from something that takes a toll on the body. Sleep does lowers a person’s metabolic rate and energy consumption. The cardiovascular system gets a break during sleep (20 to 30% reduction in blood pressure,10 to 20% reduction in heart rate).
what is the problems with the energy conservation theory
The amount of sleep people get does not correlate with how much or
how little they exercise.
• The caloric difference between humans sleeping and humans sitting
still across 8 hours is negligible (about 110 calories).
explain the Brain Processing theory
(learning and memory) – How can the brain update synaptic weights while it is currently operational and constantly receiving new information?
• Sleep gives the brain an opportunity to reorganize data and archive memories, which maybe cannot be done efficiently during the wake state.
• Synaptic modifications clearly occur during sleep
• Learning and memory are clearly impacted by sleep. The amount of slow- wave and REM sleep people get correlates with improvements in declarative and procedural memory, respectively.
• During sleep the brain appears to be actively processing information and transferring it between different areas, both within cells (with gene transcription) and between cells (through network oscillations)
explain the theory about Restoration of some kind
restore, replace, rebuild
• Maybe sleep is required to complete a particular biochemical task, some kind of repair or clean up
• The fact that total sleep time is highly correlated with all of these variables (body mass, brain mass, metabolic rate, heart rate, life span) suggests that sleep may be critical for either the distribution of nutrients or the removal of waste products.
Some evidence suggests sleep is required for efficient removal of waste products from the brain.
• It has been reported that the concentration of certain proteins in the brain increases across periods of wakefulness and decreases across periods of sleep.
• Recent research has shown that the clearance of proteins and waste products from the brain is almost nonexistent during wakefulness but really high during sleep
