9.2 Stages Of Sleep And Brain Mechanisms

Question 0

Sleep is a state that the brain actively produces, characterised by decreased response to stimuli. In contrast, ____ is an extended period of unconsciousness caused by head trauma, stroke, or disease.

Answer 0

coma

Question 1

A person on a coma has a ___ ____ of brain activity throughout the day, and little or no response to stimuli, including those that are ordinarily painful.

Answer 1

low level

Question 2

Any movements of a person in a coma are purposeless and not directed toward anything. Typically, someone in a coma ever dies or begins to recover ________.

Answer 2

within a few weeks

Question 3

Someone in a ____ ____ alternates between periods of sleep and moderate arousal, although even during the more aroused state, the person shows no awareness of surroundings.

Answer 3

vegetative state

Question 4

In a person in a vegetative state breathing is more regular, and a painful stimulus produces at least the ____ ____ of increased heart rate, breathing, and sweating. The person does not speak, respond to speech, or show any purposeful activity.

Answer 4

automatic responses

Question 5

A ____ ____ ____ is one state higher, with occasional, brief periods of purposeful actions and a limited amount of speech comprehension. A vegetative or minimally conscious state can last for months or years.

Answer 5

minimally conscious state

Question 6

____ ____ is a condition with no sign of brain activity and no response to any stimulus. Physicians usually wait until someone has shown no sign of brain activity for 24 hours before pronouncing brain death, at which point most people believe that it is ethical to remove life-support.

Answer 6

Brain death

Question 7

The ____ (EEG), records an average of the electrical potentials of the cells and fibres in the brain areas nearest each electrode on the scalp.

Answer 7

electroencephalograph

Question 8

On an electroencephalograph, if half the cells in some area increase their electrical potential while the other half decrease, they ____ ___.

Answer 8

cancel out

Question 9

The EEG record ____ or ____ when most cells do the same thing at the same time.

Answer 9

rises or falls

Question 10

A ____ is a combination of EEG and eye-movement records.

Answer 10

polysomnograph

Question 11

____ ____ are characteristic of relaxation, not of all wakefulness.

Answer 11

Alpha waves

Question 12

During sleep ____ ___, the EEG is dominated by irregular, jagged, low-voltage waves. Overall brain activity is less than in relaxed wakefulness but higher than other sleep stages.

Answer 12

stage one

Question 13

The most prominent characteristics of sleep ____ ___ are sleep spindles and K-complexes.

Answer 13

stage two

Question 14

A ____ ____ consists of 12- to 14-Hz waves during a burst that lasts at least half a second. Sleep spindles result from oscillating interactions between cells in the thalamus and the cortex.

Answer 14

sleep spindle

Question 15

A ____ is a sharp wave associated with temporary inhibition of neuronal firing.

Answer 15

K-complex

Question 16

In the succeeding stages of sleep, heart rate, breathing rate, and brain activity ____, while slow, large-amplitude waves become more common.

Answer 16

decrease

Question 17

By sleep ____ ____, more than half the record includes large waves of at least a half-second duration.

Answer 17

stage four

Question 18

Stages 3 and 4 together constitute ____ ____ (SWS). Slow waves indicate that neuronal activity is highly synchronised.

Answer 18

slow-wave sleep

Question 19

____ ____ is so named because it is deep sleep in some ways and light in others.

Answer 19

Paradoxical sleep

Question 20

Periods of rapid eye movement occurs during sleep. They called these periods ____ ___ ____ (REM) sleep and soon realised that REM sleep was synonymous with what Jouvet called paradoxical sleep.

Answer 20

rapid eye movement

Question 21

Researchers use the term REM sleep when referring to humans but often prefer the term paradoxical sleep for nonhumans because many species lack ___ ____.

Answer 21

eye movements

Question 22

During paradoxical or REM sleep, the EEG shows irregular, low-voltage fast waves that indicate increased ____ ____. In this regard REM sleep is light.

Answer 22

neuronal activity

Question 23

However, the postural muscles of the body, including those that support the head, are more relaxed during REM than in other stages. In this regard, REM is ____ ____.

Answer 23

deep sleep

Question 24

REM is also associated with ____ in males and vaginal moistening in females.

Answer 24

erections

Question 25

Heart rate, blood pressure, and breathing rate are more ____ in REM than in stages 2 through 4. In short, REM sleep combines deep sleep, light sleep, and features that are difficult to classify as deep or light.

Answer 25

variable

Question 26

In addition to its steady characteristics, REM sleep has intermittent characteristics such as ____ ____ and ___ ____.

Answer 26

facial twitches and eye movements

Question 27

The sleep stages other than REM are known as _____ (NREM) sleep.

Answer 27

non-REM sleep

Question 28

When you fall asleep, you start in stage one and slowly progressed through stages two, three, and four in order. After about an hour of sleep you begin to cycle back from stage four through stages three, two, and then REM. The sequence repeats, with each cycle lasting about _______.

Answer 28

90 minutes

Question 29

Early in the night, stages three and four predominate. Towards the morning, REM occupies an ____ percentage of the time.

Answer 29

increasing