PS 231: Chapter 10 Sleep

What are 4 things that sleep benefits?

• weight

• skin

• mental health

• immune system

Sleep quality

measures of sleep intervals and both frequency and duration of waking

whats the average amount of sleep people get per night

7 hours

How much sleep is beneficial in people?

sleeping more or less than 7 hours a day is associated with increased mortality

Biological Rhythms

a behavior with a daily rhythm of activity. Ex. sleep/wake cycle

Circadian Rhythm

biological clock, lasts about a day

Free-run

when cycles of activity drift in accordance to an endogenous circadian rhythm

Endogenous

internal

Entrainment

the process of synchronizes to a new cycle

Zietgebers

enivronemental cues that we use to entrain our rhythms to the outside world

What are 3 human zietgebers

• light

• noise levels

• meal schedules

What are 3 animal zeitgebers?

• ebb and flow of tides

• temperature

• cycles of food availability

What happens when you disrupt a rats circadian rhythm?

they start to run a little later everyday and they free-run when constant conditions are imposed.

The suprachiasmatic nucleus (SCN) is in…. and is responsible for…

the hypothalamus, organizing many of the bodys circadian rhythms.

How do we know rhythms of activity are still seen even after the SCN is isolated?

because hormone release still occurs cyclically even after the SCN is removed from the brain and kept in a disk.

What did the SCN transplant show?

that the tau mutant caused a circadian rhythm of 20 hours

What is the retinohypothamalic tract (RHT)?

it has specialized photosensitive ganglion cells in the retina and sends projections directly to the SCN.

Melanopsin

a photopigment in the ganglion cells

What are 4 of the rhythms that the SCN controls?

• heart

• pineal gland

• liver

• adrenal gland

Melatonin

hormone produced by the pineal gland that is released under the control od SCN input and helps coordinate the circadian responses throughout the body.

Whats the process of how SCN keeps time

Cl/Cy proteins turn on the Per/Cry genes —> Per/Cry proteins interfere with the Cl/Cy function —> with the Per/Cry genes OFF, the Per and Cry proteins degrade —> Cl/Cy proteins activate again

What happens when shift work disrupts rhythms?

the natural zeitgebers are unchanged, but the sleep-wake cycle must be altered

Why is indoor lighting a poor zeitgeber?

because it doesn’t have the proper wavelengths that natural lights do

What happens when jet lag disrupts rhythms?

the sleep urge is out of sync with the new time zone since the zeitgebers occur at a different time so our cycles must adapt. this takes 1 week

There is an increased risk of many types of cancers for people on the ___ side of a time zone because ___ and ___

west, they experience fewer days with natural morning light, so they need to use electric lights (which are poor zeitgebers) for light in the morning, they receive an extra hour of natural light in the evening which isnt good for sleep and results in reduced sleep duration for around 19 minutes.

Electroencephalogram (EEG)

reveals brainwaves

Electrooculogram (EOG)

records eye movements seen during rapid eye movement (REM) sleep

Electromyogram (EMG)

detects loss of activity in neck muscles during some sleep stages

What are the 4 waveforms and what attentional states are they associated with?

• Beta (15-30 Hz): Awake, normal alert consciousness

• Alpha (9-14 Hz): Relaxed calm, meditation, creative visualisations

• Theta (4-8 Hz): Deep relaxation and meditation, problem solving

• Delta (1-3 Hz): Deep, dreamless sleep

Stage 1 sleep EEG

Similar to awake EEg with theta and vertex spikes

Stage 2 sleep EEG

K complexes: large up and down deflection and sleep spindles: bursts of 12-14 Hz waves

Stage 3/4 sleep EEG

large and slow (1/sec) delta waves; Slow wave sleep (SWS)

Kleitman and Asernisky (1953) discovered what?

REM (AKA paradoxical) sleep, a period of desychronized EEG activity that is similar to awake sleep. includes dreaming, eye movements, and absence of muscle tone

SWS occurs mostly ___

early

Bouts of REM sleep are usually and _ as sleep progresses

less than 30 min, longer

there are about __ series per night

4-5

What are 4 things that happen during SWS?

• cerebral metabolism decreases by 75%

• the brain restores areas that were active during the day

• increased release of growth hormone (GH)

• “brainwashing” or waste removal

What are 4 things that happen during REM?

• darting eyes, fluctuations in heart and breathing rates

• increased cerebral blood flow and oxygen use

• PGO waves

• dreaming

Freudian Dream Theory

dreams allow us to reconcile with unacceptable repressed wishes

Activation-Synthesis Theory (Hobson & McCarley 1977)

dreams result from the cortex’s attempt to make sense of random brain activity

Neurocognitive Theory

dreaming is similar to waking consciousness but disconnected from external stimuli and self-awareness

What are micro sleeps?

happens while awake but people are unaware that they fell asleep

What happened in Rhandy Gardners project?

he stayed awake for 11 days and showed symptoms of incoordination, hallucination and disorientation

What happens during Partial Sleep Deprivation?

It can produce acute and chronic effects on cognition (like attention and reaction time), mood, and health and memory

What are the 3 reasons why we sleep?

• cognitive function

• energy conservation

• restoration/repair