# data[].attributes.body
* External factors- meal times, stress, exercise will influence sleep times and durationns
* sleep hygiene- practice of consciously following daily guidelines to ensure effective sleep
* drugs such as marijuana act as sedatives : encouraging sleep
* stimulants such as caffeine: reduce sleep
* food such as carbohydrates: encourage drowsiness and sleep
* food contain tyramine such as nuts and avocado may make you awake at night

SLEEP WAKE HOMEOSTASIS
* internal biochemical system that regulates body's internal environment: body's temperature
* the larger we awake, the stronger desire to sleep- the longer we've been asleep, the more the pressure to sleep will occur
* naturally produce in body's cerebrospinal fluid
* one of its substance: odenosine which operates as neuromodulator in brain
* odenosine inhibits many bodily process : neurotransmitter, norepinephrine, acetylcholin, serotonin
* odenosine is a kind of sleep debt that buiks up in basal forebrain
* high level of odenosine leads to slepiness
* caffeine acts as odenosine antagonist: inhibits slepiness effect
* sleep wake homeostasis often refer to non-REM sleep and slow wave sleep
* its a kind of switch function: ether you awake or asleep
* orexin is related tohypothalamus tegion of the brain
*  if the condition is uitable to non-REM , rem is inhibited and vice versa

saiyidatul aisyah (1523736)
nuratikah hafizah 1521162)
nor 'aifa bazilah (1525384)
Nur syahirunisa (1527526)
nur sakeenah (1527454)

# data[].attributes.body
Hajrah & Atini
+ Process of sleep-wakefulness are mediated by networks of neurons which produce neurotransmitters.
+ The activation of the process  are the results of increasing homeostasis drive to seep and changes in circadian clock.
+ When certain areas of the brain are active, the cerebral cortex (high thinking process) is aroused. At the same time, the areas that are responsible for sleep is inhibited, hence, the wakefulness. When the sleep-promoting areas are most active, the areas of wakefulness are inhibited.
+ Wakefulness is regulated in the brainstem, hypothalamus and basal forebrain.

+ The ventrolateral preoptic nucleus (VLPN) of hypothalamus is the sleep-switch
+ Neurons in it inhibit activity in the brainstem (wakefulness), causing sleepiness.
+ Mutual inhibiton = During wakefulness, those areas of the brain that are active, also stimulate the cerebral cortex to inhibit the neurons of VLPN

+ Neurotransmitters that are involved:
a) Histamine (master of wakefulness), dopamine, norepinephrine, serotonin =  promotes wakefulness, decrease REM sleep.
b) Orexin =
1. regulates wakefulness, arousal and appetite.
2. deficiancy = sleep-state instability, sleep disorder (narcolepsy)
c) Serotonin = released throughout the day, stimulating particular area of hypothalamus which in turn inhibits a different part of it and has the effect of encourage sleep.
d) Melatonin = converted from serotonin in pineal gland in the brain. Its production increase in the evening, causing drowsiness and lowering body temperature. Its production decreases to its normal level by early morning. Melatonin regulates sleep-wake cycle by inhibit the circadian alerting system in the suprachiasmatic nucleus. Its production is inhibited by light (encodes the seasons to some extent which some animals use in their mating practices ; in non-equatorial regions)
e) cortisol = stress hormone. Begins to increase towards the end of the night to anticipate the stress of the day. Reaches its peak about 20-30 minutes after waking (cortisol awakening response)

+ Thalamus serves as the gatekeeper to the cerebral cortex. It will disconnect the cortex from most internal and external signals when wakefulness is interrupted (signal to sleep)
+ Thalamus imparts the slow brain waves to the cortex. If thalamus is damaged, it may cause a sleep disorder called fatal familial insomnia (FFI) in which malformed proteins (prions) attack the thalamus, which effectively makes sleep impossible.

+ Pons = population of neurons in pons are selectively active during REM sleep.
+ When acethylcholine activate pons, two other areas in the pons are simultaneously inhibited in order for REM sleep to occur. Inhibitory signals are also sent from the pons to the spinal cord that cause temporary muscle paralysis
+ other neurotransmitters (norepinephrine,serotonin,histamine) that create muscle activity are shut down.

+ the switching between REM sleep and non-REM sleep is regulated by several complex interactions between REM-on and REM-off neurons
+ at night, after the body has received restorative non-REM sleep, adenosine levels will decline which in turn promotes wakefulness.
+ Cytokines (cell-signaling protein molecules) = chemicals produced by immune systems while fighting an infection is also a powerful hypnogenic chemicals. This is why infectious diseases; flu tend to make us to feel sleepy.

# data[].attributes.body
It can be thought as a kind of internal timer or counter that generates homoestatic sleep drive .

How does it work
-The longer we have been awake, the stronger the desire to sleep
- the longer we have been asleep, the greater the likelihood to fall a sleep
- when ww habe sleep dissipate we tend to stay awake

# data[].attributes.body
Fatin Shuhada
Nik Norafifah
Natasha
Nazeha

Circadian clock (also known as the biological clock, body clock, circadian pacemaker, circadian system, circadian oscillator, etc) centred in the hypothalamus region of the basal forebrain

The most important hormones affected by the circadian clock as they affect sleep

1. melatonin (produced in the pineal gland in the brain, chemically causes drowsiness and lowers body temperature)

2. cortisol (produced in the adrenal gland, used to form glucose or blood sugar and to enable anti-stress and anti-inflammatory functions in the body)

# data[].attributes.body
-regulated by twonseparate mechanisms.
1.circadian rythm -process c, regulation of the body internal processes and alertness level, govern by the internal biological/circadian clock
2.sleep wake homeostasis- process S, accumulation of hypnogenic substances in the brain, generates a homeostasis sleep drive
-influenced by genes
-external factor eg: food, drug, ambient etc effect on individual sleep wake cycle.
-circadian clock centered in hypothalamus, main mechanism that consist of timing of sleep and independent of the amount of preceding sleep or wakefulness.

Circadian rythm
-not sufficient to cause and regulate sleep. Inbuilt propensity toward sleep-wake homeostasis which is balanced against the circadian element.

Sleep wake homeostasis
-internal biochemical system that creates as a kind of timer or counter generating a homeostasis sleep drive or pressure to sleep and regulating sleep intensity.
-the longerrhe longer we have been awake, the stronger the desire need to sleep

Neurological mechanisms of sleep

# data[].attributes.body
Fatin Shuhada
Nik Norafifah
Natasha
Nazeha

·         Animals , plants and humans have built-in circadian rhythm.

·         Adjusted to environment by external cues, referred to as Zeitgebers.

o   daylight is the most important.

o   food, drugs, meal times, stress, daily schedules.

·         Human circadian rhythm is regulated by internal biological clock in brain.

o   Circadian clock (also known as the biological clock, body clock, circadian system, circadian pacemaker, circadian oscillator, etc.) centred in the hypothalamus region of the basal forebrain.

o   reset itself each day

o   varies among different individuals, between 23.5 - 24.5 hours in humans

·         What does the brain's circadian clock do?

1.  regulates sleeping and feeding patterns

2. alertness

3. core body temperature

4. brain wave activity

5. hormone production

- Melatonin and cortisol is produced during sleep.
-Melatonin is produced in the pineal gland in the brain, chemically causes drowsiness and lowers body temperature.
-Cortisol is produced in the adrenal gland, used to form glucose or blood sugar and to enable anti-stress and anti-inflammatory functions in the body.

- Growth hormone secreted especially during non-REM sleep. Likewise with testosterone.

- Thyrotropin is suppressed during sleep.

6. regulation of glucose and insulin levels

7. urine production

8. cell regeneration

·         Towards the end of sleep period:

o   minimum core body temperature: 4:30-5am in adults

o   maximum melatonin production: begins at around 8-9pm and stops around 7-8am.

·         Deepest tendency to sleep: 2-3am and 2-3pm ("post-lunch dip").

During daylight:

- Melatonin is completely absent in the morning.

- Suprachromatic nucleus (SCN) in hypothalamus is much more active.

Irregular sleep patterns of newborn babies occur as circadian rhythms take some time to develop.

Can be adjusted according to an individual's chronotypes.

Timing of circadian period encoded in their genes.

Hence, some people can be considered as "morning person" and "evening person"! :D

# data[].attributes.body
By: arina, hadjer, fathiah, lani, husna comel

2 process models (internal factors)
1.  circadian rhythm (process c)
-Regulate body's internal processes and alertness level
-Controlled by circadian clock

2. sleep wake homeostasis (process s)
-Accumulation of the sleep inducing substances in the brain
-The more we stay awake, the more we get sleepy

For someone to sleep, they need both processes to induce sleeping as circadian rhythm and sleep wake homeostasis are compliment with each other.

External factors that induce sleep
- temperature
- naps
- stress
- exercise
- drugs
There are two types
1. Sedative : encourage sleep (eg: alcohol, marijuana)
2.stimulant : distrupt sleep(caffeine, cocaine)

Both types of drug has its own side effects and can cause addiction to the person

Foods and drink
1. Tyrptophan (example, bananas, milk) and carbohydrate : encourage sleep and drowsiness
2. Tyramine (eg; raspberries, nuts): make you stay awake

CIRCADIAN RHYTHM
-influence by the external cues (daylight)
- naturally synchronised and reset itself each day
-also known as biological clock, body clock, circadian system
- centered in the hypothalamus
- Circadian periods are different among individuals, ranging between 23.5 and 24.5

# data[].attributes.body
By: Yomna & Hajrah & Atini :)

# data[].attributes.body
sleep-wake hemeostasis
- brain region
mechanism

# data[].attributes.body
physiological mechanism
-brain region
- mechanism

# data[].attributes.body
circadian rhythm
-brain region
- mechanism