Topic 5 - Sleep Flashcards
Which three hormones follow a diurnal cycle?
- Melatonin
- Cortisol
- Growth hormone
What does the hypothalamus regulate?
The body’s circadian rhythms
Why do we need to sleep?
So that waste products can be removed from the brain
What is the glymphatic system?
The system which is responsible for cleaning up the brain
How does the glymphatic system work?
It uses CSF to flush away waste
How much of our lives do we spend sleeping?
About a third
What chemicals help to induce sleep?
- Melatonin
* Adenosine
During which phase of sleep does DNA repair itself?
Deep sleep
Fewer than how many hours of sleep a night is associated with a 4.5x increased risk of strokes?
Less than 6hrs
What conditions can be linked to a chronic lack of sleep?
- Obesity
* Diabetes
What is one of the byproducts of energy sources being used in the brain?
Adenosine
What happens as adenosine levels increase?
It creates sleep pressure - increases the urge to sleep
How does caffeine stop us from feeling sleepy?
It blocks adenosine’s receptor pathways
Name some of the negative effects of sleep deprivation.
- Sensory/vision disruption
- Inflammation
- High blood pressure
- Lack of coordination/poor reaction times
- Hormonal imbalances
- Concentration/memory issues
- Hallucinations
- Paranoia
- Death
How much of their time do infants spend in REM sleep?
About 100%
What are the two main phases of sleep?
- REM - rapid eye movement
* NREM - non-rapid eye movement
How many stages of NREM sleep are there?
4
What are some of the other names for NREM sleep?
- Quiet
- Deep
- Slow-wave
What happens if you wake someone from NREM sleep?
They will be very confused and have poor physical coordination
What are the other names for REM sleep?
- Active
* Paradoxical
Why is REM sleep also known as paradoxical sleep?
Because the brain wave pattern during REM sleep is similar to that during wakefulness
If we were to sleep-walk, which phase of sleep would this occur during?
NREM
What are some of the purposes of sleep?
- Maintenance of homeostatic equilibrium
- Conservation of energy
- Tissue repair
- Memory consolidation
- Fighting infection
Which hormone can the sleep cycle affect the secretion of?
What does that hormone do?
- Leptin
* Influences body weight and appetite
How is energy conserved by sleeping?
Consumption of ATP falls, which reduces the body temperature
Production of what in the brain increases at night?
Proteins
How can the immune system affect sleep?
It produces cytokines, which have sleep-inducing properties
What are the two major external stimuli which affect sleep in humans?
- Light(/darkness)
* The alarm clock
How many clock genes do humans have?
At least eight
How many of the clock genes which humans have are implicated in sleep disorders?
Two
Which type of hormone is melatonin?
A peptide hormone
What is a peptide?
A short chain of amino acids which are connected to each other in a sequence by bonds called peptide bonds
What is a peptide bond?
A covalent bond formed between two amino acids
What is the pineal gland?
The gland deep in the brain, behind the pituitary gland, which is has cells that secrete melatonin
What are melanopsin cells?
Specialised cells in the retina of the eye which detect light
When light levels fall, where in the brain are signals sent to via the optic nerve?
The suprachiasmatic nucleus (SCN) in the hypothalamus
What is the venterolateral preoptic nucleus involved in?
The initiation of sleep, together with melatonin
What is the reticular formation?
What does it do?
- 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
What type of hormone is growth hormone (GH)?
A water-soluble peptide
When during sleep is the most growth hormone (GH) released?
During the first hours of sleep
How does growth hormone (GH) stimulate bone growth?
It increases calcium retention and mineralisation of bone, and increases muscle mass by stimulating protein synthesis. It also promotes increased rates of cell division
Why does growth hormone stimulate the breakdown of triglycerides in adipocytes and the breakdown of glycogen in the liver?
These fuel molecules are required as a source of energy for the formation of new bone and muscle mass
Why mght bodybuilders think they need a diet high in protein?
In order to have enough dietary amino acids to build new muscle and bone (though their standard diet is likely already sufficient enough!)
What are growth factors?
Proteins which act as signalling molecules to help regulate growth, normally in a cell-type or tissue-specific manner
What are cytokines?
Signalling molecules which are used by the immune system
In the circadian cycle, when does the secretion of cortisol peak?
Just before waking, and then declines throughout the day
Which region of the brain controls the release of cortisol?
The hypothalamus
What are the essential metabolic processes which are facilitated by cortisol?
- Breakdown of proteins
- Glucose synthesis from proteins
- Breakdown of lipids
- Resorption of calcium from bone
