235 biological rhythms

are fluctuations that occur over a roughly 24hour period. Processes that fluctuate on a circadian cycle include sleep and wakefulness, hormonal concentrations in blood and feeling

Circadian rhythms

The internal clock is synced up with the external environment using cues called _______, which signal something about the time of day

zeitgebers

For human beings, an important zeitgeber is a __________ – such as the rapid increase in light levels that occurs when the sun comes up

phase shift in light

If a human being is kept in constant dim light, the free-running circadian clock will cycle once every

25 hours

The ___________ of the hypothalamus (SCN) contains the circadian clock

suprachiasmatic nucleus

SCN gets direct input from a population of _______ in the ______ that carry information about phase shifts in light levels. This pathway is specifically designed to sync the circadian clock up with the time of day

ganglion cells and retina

SCN sends information to a variety of places, including the ________ , which releases the hormone ________ at night in order to facilitate sleep

pineal glandand melatonin

The retinal ganglion cells that project to the SCN are actually _______ – they do not need to get info from rods & cones, but instead respond to light  _____

light-sensitive and directly

These cells are especially sensitive to ________. Thus – late night screen time can send an erroneous message to your SCN about time of day, _______ your sleep cycle

blue light and dysregulating 

SCN neurons make two proteins, ___ and _____. They form a dimer, and

the dimer activates two genes, period and cryptochrome

clock and cylce 

SCN neurons make two proteins, clock and cycle. They form a dimer, and

the dimer activates two genes, _____ and ______

period and cryptochrome

Two proteins result (also called period and cryptochrome). These also form a dimer, which inhibits the ________(thus preventing it from activating period and cryptochrome genes)

clock/cycle dimer

The ________ dimer slowly breaks down, releasing the clock/cycle dimer from inhibition. This process takes about 24 hours and is the molecular basis of the circadian rhythm

period/cryptochrome

released from specialized retinal ganglion cells onto SCN neurons mimics the effect of clock/cycle, thus syncing this molecular clock with daylight

Glutamate

is a technique that measures the combined activity of many neurons (i.e. brain waves) and can be used to differentiate the distinct stages of waking and sleep

EEG

Being awake is characterized by EEG activity that is ___________across the cortex (synchronized waking activity usually only occurs during seizure)

desynchronized

Waking brain waves tend to be high _______ and low ______

frequency and amplitude

There are two broad stages of sleep: __________ (REM) sleep and _______ sleep

rapid eye movement and non-REM

Non-REM sleep comes first, and is divided into ______  with distinct brain-wave patterns. During the early part of non-REM sleep the heart rate slows and muscles relax. When awakened during early non-REM sleep, people often deny that they were sleeping

3 phases

Non-REM sleep comes first, and is divided into 3 phases with distinct brain-wave patterns. During the early part of non-REM sleep the _______ slows and ______ relax. When awakened during early non-REM sleep, people often deny that they were sleeping

heart rate and muscles

The final phase of non-REM sleep, also called ________, involves high amplitude brain waves and (non-seizure) _________ of activity across the cortex

slow-wave sleep and synchronization

REM sleep is also cause _________ because brain wave activity is highly similar to activity observed during waking

paradoxical sleep

REM sleep involves rapid, darting movement of the eyes (hence the name). There is also a complete loss of _________. You are most likely to report that you were dreaming if awakened If awakened during REM sleep

muscle tension

Thus, the pattern of cortical activity observed during waking and REM sleep seems to be associated with conscious experience

conscious experience

In a typical night of healthy, ____hour sleep:

7-8 and 80% is non-REM sleep, 20% is REM sleep

The deepest phase of non-REM sleep, _______, tends to occur earlier in the night. Slow-wave sleep is thought to be the most restful and restorative

slow-wave sleep

This allows migratory birds to remain partially conscious while also being partially asleep midflight, which is particularly useful when there is no obvious place to land and shelter

Some animals have developed the ability to sleep one brain hemisphere at a time

you sleep more, and have a higher proportion of REM sleep, when you’re younger (though the exact purpose of this is unknown)

Developmental

during sleep, rats show patterns of brain activity associated with a maze they learned the day before. This activity, which occurs during slow-wave sleep, may promote memory storage

Memory

Growth hormones tend to be released during _________ specifically

slow-wave sleep

Proper sleep is essential for

immune function.

Materials used up during waking hours, such as proteins, are rebuilt or restored.

are rebuilt or restored.

Sleep drives clearance of ______ from adult brain by increasing flow of CSF through extracellular space.

metabolites

Metabolites include proteins linked to _________ diseases, like Alzheimer’s.

neurodegenerative

Neurons in the ___________ that produce the non-classical peptide neurotransmitter _____ are thought to coordinate systems in the brain that mediate wakefulness. They receive input from SCN

lateral hypothalamus and orexin

Neurons in the lateral hypothalamus that produce the non-classical peptide neurotransmitter orexin are thought to coordinate systems in the brain that mediate wakefulness. They receive input from ____

SCN

Lateral hypothalamus neurons release ______ onto neurons in the ______ which spans the pons and medulla of the hindbrain and sends axons broadly across the brain

orexin and reticular formation

Electrical stimulation of the reticular formation causes animals to wake from sleep, while destruction of this area leads to ______. The reticular formation also promotes the desynchronization of brain waves across the cortex

persistent sleeping

Electrical stimulation of the reticular formation causes animals to wake from sleep, while destruction of this area leads to persistent sleeping. The reticular formation also promotes the ______ of brain waves across the cortex

desynchronization

is a disorder in which overwhelming sleepiness occurs very suddenly and unpredictably.

Narcolepsy

Humans with narcolepsy have been shown to possess reduced numbers of _______ neurons

orexin

Neurons in the _________  (VLPO) of the hypothalamus do the opposite of orexin neurons – they release _____ onto neurons in the reticular formation, thus inhibiting it and decreasing wakefulness

ventrolateral preoptic area and GABA

Both VLPO and orexin neurons are coordinated by the SCN in order to

sync periods of waking and sleep with the circadian clock

______ is a brief inability to move after waking. The _______ is responsible for the loss of muscle tension that occurs during sleep – in some cases, however, it may become active too early or for too long

Sleep paralysis and dorsal pons

The opposite problem is __________ in which a there is no loss of muscle tension during REM sleep. Individuals with this issue can _____ their dreams in the real world while remaining asleep

REM behavior disorder and act out