Sleep

Question 1

Polysomnography

Answer 1

A set of physiological measures that includes electroencephalography, electrooculography, and electromyography.

Question 2

Electrooculography (EOG):

Answer 2

Recording of eye movements through changes in the electrical activity of eye muscles.

Question 3

Electromyography (EMG):

Answer 3

Recording of movements of the body through measuring changes in the electrical activity of muscles.

Question 4

Alpha ( 8 to 13 hz) , beta( 13 to 30 hz) , theta 4 to 8 hz , and delta 0.5 to 4 hz

Answer 4

Brain waves that differ in amplitude and /or frequency identified by an EEG

Question 5

NREM

Answer 5

Non-rapid eye movement sleep . Sleep that s subdivided into 4 stages of progressively deeper sleep
75 % of our sleep are spent there.
As sleep progresses, the amount of time spent in the deeper stages of sleep is reduced and the time spent in REM sleep is increased.

Question 6

Stage 1 sleep

Answer 6

transition between wakefulness and deeper stages of sleep. Stage 1 is characterized by theta waves, which are of slightly higher amplitude compared to that of beta and alpha waves but are of lower frequency (3 to 7 Hz).

Question 7

Stage 2 sleep ( sleep spindles and K-complexes )

Answer 7

Sleep spindles are series of high-frequency spikes of activity lasting anywhere from 0.5 to 1.0 seconds.
K-complexes are slightly negative deflections in a wave (the wave’s movement is exaggerated downward) followed by a positive deflection (exaggerated upward).

Stage 2 is a light form of sleep from which a person is easily awakened.

Question 8

Stage 3 and 4 ( slow waves sleep )

Answer 8

These stages are marked by high-amplitude and low-frequency wavelengths, ranging from 1 to 4 Hz, known as delta waves
The appearance of delta waves is associated with stage 3. Stage 4 sleep is characterized by delta waves consisting of more than 50% of recorded brain waves. Stages 3 and 4 are also known as slow-wave sleep (SWS).

Question 9

REM

Answer 9

REM sleep is marked by brain activity that resembles wakefulness. The rhythm observed during REM sleep is remarkably similar to that of beta waves. For this reason, REM sleep is sometimes referred to as paradoxical sleep.
the eyes are moving back and forth under the closed eyelids.
At the same time, there is a significant loss of muscle tone resulting in the sleeper becoming relatively paralyzed as detected by an EMG.
REM sleep is the sleep stage mostly associated with dreams. It was, therefore, hypothesized that this temporary paralysis occurs to prevent people from acting out their dreams.

25 % of sleep

Question 10

wakefulness

Answer 10

The waking state is characterized by what are known as beta waves. These are low-amplitude waves of high frequency, ranging from 13 to 30 Hz.

Question 11

Relaxed state

Answer 11

relaxed state, alpha waves, which are more regular and of lower frequency, are observed. Alpha waves range from 8 to 13 Hz. These waves become more frequent if the relaxing person’s eyes are closed.

Question 12

Factors that control the wake/ sleep switch :

1- homeostatic influence :

Answer 12

the degree of wakefulness is related to the accumulation of somnogens that lead to the homeostatic drive for sleep.

Question 13

somnogens.

Answer 13

Substances in the body that produce sleep

Question 14

2- Circadian influence

Answer 14

circadian rhythm : Physiological, behavioral, or psychological events that occur over an approximate 24-hour cycle.
they can be Entrained rhythm or Free running rhythm

Question 15

Entrained rhythm

Answer 15

A rhythm regulated by external cues, such as light or heat.

Question 16

Free running rhythm:

Answer 16

A rhythm that is self-regulated, not requiring any external cues.

Question 17

Suprachiasmatic nucleus (SCN)

Answer 17

The region of the hypothalamus thought to control circadian rhythms (sometimes called the master clock).
he SCN is influenced by light-dark cycles through projections from photoreceptor cells in the retina that contain the photopigment melanopsin

Question 18

Melanopsin

Answer 18

A pigment in certain photoreceptor cells of the retina, which influences the light-dark cycle through projections to the suprachiasmatic nucleus.

Question 19

Retinohypothalamic projections

Answer 19

The projections of photoreceptors containing melanopsin from the retina to the hypothalamus.
his ultimately leads to the release of melatonin from the pineal gland shortly before sleep. In turn, melatonin binds to receptors in the SCN, closing a feedback loop that provides the brain with a mechanism for determining circadian time.

Question 20

Zeitgebers:

Answer 20

Factors in the environment that influence circadian rhythms.

Question 21

wakefulness hormones

Answer 21

norepinephrine, serotonin, histamine, glutamate, and acetylcholine. he neuropeptide hypocretin (also known as orexin) is important for the maintenance of wakefulness.

Question 22

Sleep hormones

Answer 22

GABA, glutamate, and adenosine. melanin are also involved in promoting sleep. These chemicals, which promote sleep, also suppress the activity of the excitatory neurotransmitters that promote waking.

Question 23

Ascending arousal system (AAS)

Answer 23

A wakefulness-promoting system that includes areas of the brainstem.
includes the pedunculopontine/laterodorsal tegmental nuclei (PPT/LDT), locus coeruleus (LC), raphe nucleus (RN), and tuberomammillary nucleus (TMN), which are the sources of cholinergic, noradrenergic, serotonergic, and histaminergic neurons, respectively.
Projections from the AAS excite the cortex through two distinct pathways, an indirect pathway and a direct pathway.
he indirect pathway consists of cholinergic neurons in the PPT and LDT that activate the cortex through connections in the thalamus. The direct pathway (Figure 9.23b) consists of noradrenergic, serotonergic, and histaminergic neurons situated in the LC, RN, and TMN, respectively, that directly activate the cortex.

Question 24

Executive system for wakefulness:

Answer 24

Activity in the AAS itself is stimulated by the input from orexinergic neurons in the lateral hypothalamus A system that includes orexinergic neurons in the lateral hypothalamus.

Question 25

Sleep maintenance

Answer 25

Sleep is maintained by inhibitory connections to the orexinergic neurons of the LH and histaminergic neurons of the TMN from GABA and galanin neurons in the ventrolateral preoptic area of the hypothalamus (VLPO).

Question 26

wakefulness maintenance

Answer 26

maintenance of wakefulness occurs when orexin neurons in the LH stimulate the LC, RN, and TMN neurons of the AAS. At the same time, neurons in the VLPO are inhibited by projections from neurons in the AAS.