Topic 5 - Sleep

Question 1

Which three hormones follow a diurnal cycle?

Answer 1

• Melatonin
• Cortisol
• Growth hormone

Question 2

What does the hypothalamus regulate?

Answer 2

The body’s circadian rhythms

Question 3

Why do we need to sleep?

Answer 3

So that waste products can be removed from the brain

Question 4

What is the glymphatic system?

Answer 4

The system which is responsible for cleaning up the brain

Question 5

How does the glymphatic system work?

Answer 5

It uses CSF to flush away waste

Question 6

How much of our lives do we spend sleeping?

Answer 6

About a third

Question 7

What chemicals help to induce sleep?

Answer 7

• Melatonin

* Adenosine

Question 8

During which phase of sleep does DNA repair itself?

Answer 8

Deep sleep

Question 9

Fewer than how many hours of sleep a night is associated with a 4.5x increased risk of strokes?

Answer 9

Less than 6hrs

Question 10

What conditions can be linked to a chronic lack of sleep?

Answer 10

• Obesity

* Diabetes

Question 11

What is one of the byproducts of energy sources being used in the brain?

Answer 11

Adenosine

Question 12

What happens as adenosine levels increase?

Answer 12

It creates sleep pressure - increases the urge to sleep

Question 13

How does caffeine stop us from feeling sleepy?

Answer 13

It blocks adenosine’s receptor pathways

Question 14

Name some of the negative effects of sleep deprivation.

Answer 14

• Sensory/vision disruption
• Inflammation
• High blood pressure
• Lack of coordination/poor reaction times
• Hormonal imbalances
• Concentration/memory issues
• Hallucinations
• Paranoia
• Death

Question 15

How much of their time do infants spend in REM sleep?

Answer 15

About 100%

Question 16

What are the two main phases of sleep?

Answer 16

• REM - rapid eye movement

* NREM - non-rapid eye movement

Question 17

How many stages of NREM sleep are there?

Answer 17

4

Question 18

What are some of the other names for NREM sleep?

Answer 18

• Quiet
• Deep
• Slow-wave

Question 19

What happens if you wake someone from NREM sleep?

Answer 19

They will be very confused and have poor physical coordination

Question 20

What are the other names for REM sleep?

Answer 20

• Active

* Paradoxical

Question 21

Why is REM sleep also known as paradoxical sleep?

Answer 21

Because the brain wave pattern during REM sleep is similar to that during wakefulness

Question 22

If we were to sleep-walk, which phase of sleep would this occur during?

Answer 22

NREM

Question 23

What are some of the purposes of sleep?

Answer 23

• Maintenance of homeostatic equilibrium
• Conservation of energy
• Tissue repair
• Memory consolidation
• Fighting infection

Question 24

Which hormone can the sleep cycle affect the secretion of?

What does that hormone do?

Answer 24

• Leptin

* Influences body weight and appetite

Question 25

How is energy conserved by sleeping?

Answer 25

Consumption of ATP falls, which reduces the body temperature

Question 26

Production of what in the brain increases at night?

Answer 26

Proteins

Question 27

How can the immune system affect sleep?

Answer 27

It produces cytokines, which have sleep-inducing properties

Question 28

What are the two major external stimuli which affect sleep in humans?

Answer 28

* Light(/darkness) | * The alarm clock

Question 29

How many clock genes do humans have?

Answer 29

At least eight

Question 30

How many of the clock genes which humans have are implicated in sleep disorders?

Answer 30

Two

Question 31

Which type of hormone is melatonin?

Answer 31

A peptide hormone

Question 32

What is a peptide?

Answer 32

A short chain of amino acids which are connected to each other in a sequence by bonds called peptide bonds

Question 33

What is a peptide bond?

Answer 33

A covalent bond formed between two amino acids

Question 34

What is the pineal gland?

Answer 34

The gland deep in the brain, behind the pituitary gland, which is has cells that secrete melatonin

Question 35

What are melanopsin cells?

Answer 35

Specialised cells in the retina of the eye which detect light

Question 36

When light levels fall, where in the brain are signals sent to via the optic nerve?

Answer 36

The suprachiasmatic nucleus (SCN) in the hypothalamus

Question 37

What is the venterolateral preoptic nucleus involved in?

Answer 37

The initiation of sleep, together with melatonin

Question 38

What is the reticular formation? | What does it do?

Answer 38

* A set of interconnected nuclei which span the brain stem and neurons in the brain * It stimulates the thalamus during wakefulness. Its decreased activity levels cause a decrease in the level of consciousness

Question 39

What type of hormone is growth hormone (GH)?

Answer 39

A water-soluble peptide

Question 40

When during sleep is the most growth hormone (GH) released?

Answer 40

During the first hours of sleep

Question 41

How does growth hormone (GH) stimulate bone growth?

Answer 41

It increases calcium retention and mineralisation of bone, and increases muscle mass by stimulating protein synthesis. It also promotes increased rates of cell division

Question 42

Why does growth hormone stimulate the breakdown of triglycerides in adipocytes and the breakdown of glycogen in the liver?

Answer 42

These fuel molecules are required as a source of energy for the formation of new bone and muscle mass

Question 43

Why mght bodybuilders think they need a diet high in protein?

Answer 43

In order to have enough dietary amino acids to build new muscle and bone (though their standard diet is likely already sufficient enough!)

Question 44

What are growth factors?

Answer 44

Proteins which act as signalling molecules to help regulate growth, normally in a cell-type or tissue-specific manner

Question 45

What are cytokines?

Answer 45

Signalling molecules which are used by the immune system

Question 46

In the circadian cycle, when does the secretion of cortisol peak?

Answer 46

Just before waking, and then declines throughout the day

Question 47

Which region of the brain controls the release of cortisol?

Answer 47

The hypothalamus

Question 48

What are the essential metabolic processes which are facilitated by cortisol?

Answer 48

* Breakdown of proteins * Glucose synthesis from proteins * Breakdown of lipids * Resorption of calcium from bone