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Medical and Applied Physiology > Fatigue & Sleep > Flashcards

Flashcards in Fatigue & Sleep Deck (14):

Physical & Mental Fatigue

Physical Fatigue

Synonymous with muscle fatigue: reduced power and movement and is associated with:

•reduced alertness,

•reduced work output,

•weaker and slower muscle contraction,

•loading of respiratory , circulatory and neuromuscular function,

•decrease in exertion and endurance time,

•increase in lactate accumulation,

•increase in core temperature

Mental Fatigue

Denotes reduction in efficiency, disclination for any effort, reduced alertness and mental performance and associated with


•Feelings of inhibition and impaired activity

•No desire for physical or mental effort

•Heavy and drowsy feeling

•Distress if can't allow ourselves to relax


Indicators of fatigue

•Biochemical- lack of chemical indicator of sleep

•EOG- motor connection between eye and brain

•Heart rate

•Psychomotor tests

•Mental tests

•Fatigue questionnaires


•EEG most predictive and reliable


Drowsiness/Fatigue phase

Drowsiness/Fatigue phase

•Transitional: between awake and changes in alpha

•Transitional- post transitional: characteristics of both

•Post transitional: frontocentral slowing, stage 1 sleep

•Arousal: emergence from drowsiness; beta and alpha

Transitional Phase

•Increase and or decrease in alpha amplitude: centro frontal alpha, temporal alpha

•Increase in slow activities: posterior delta/theta + alpha, centro frontal delta/theta + alpha, temporal delta/theta

Transitional to Post transitional

•Frontocentral beta, generalised 3-5 Hz slowing, mid temporal theta

Post transitional

•Posterior and frontocentral slowing

- centro frontal beta and alpha, posterior alpha


Chronic Fatigue

Chronic Fatigue

•Perceived as intense compared to amount of activity performed

•Last longer than 1 month, has cumulative effect and affect life quality

•Occur due to many disease: cancer, cardiac, end stage renal, chronic lung, hepatitis C, arthritis, HIV/AiDS, neurologic disorders such as MS, post polio syndrome, parkinson disease

Chronic Fatigue Management

•Pathologic links: include insomnia, anemia, stress, weakness or wasting

•Anemia common with HIV/AIDS, renal disease and cancer patients: can be treated with forms of erythropoietin- hormone produced by kidney normally

•Insomnia due to anxiety, depression, nocturia and pain: can be treated both pharmacologically and non pharmacologically

•Loss of muscle mass strength and endurance due to arthritis, MS, immobility, HIV/AIDs= may be reduced with aerobic exercise


Neural Basis of sleeping

•Circadian rhythms- 24 hr biological cycles: regulation of sleep/ other bodily functions

•Physiological pathway of biological clock: light levels→ retina→ suprachiasmatic nucleus (SCN) of hypothalamus→ pineal gland→ secretion of melatonin

•Melatonin and circadian rhythms: hormone produced by pineal gland helps regulate sleep wake cycle, large numbers of melatonin receptors in SCN suggest feedback loop between SCN and pineal gland, melatonin used to treat sleep disorders linked to shifts in circadian rhythms


Sleep/Waking studies

•Instruments: Electroencephalograph (brain electrical activity), electromyograph ( muscle activity), electrooculographic (eye movements), other bodily functions observed

•Polysomnography: assess of sleep patterns, medication effects, physical and other ailments, sleep related disturbances such as sleep disordered breathing, periodic limb movements etc


Stage of Sleep

•Classic definition (R&K 1968): wakefulness, non Rem sleep stages: 1. drowsiness/light sleep → 2. Light sleep→ 3. Slow wave sleep/deep sleep → 4. Slow wave sleep/very deep sleep, REM- rapid eye movement

•Updated definition has stage 3 and 4 combined ( AASM, 2007): wake, non REM: N1- ~ R&K stage 1→ N2 ~ R&K stage 2 → N3- stage 4 and 3 combined since no physiological or clinical basis for difference, REM- stage R


Sleep cycle overview

Sleep and learning- does it occur?

•Research: but are people really asleep when materials presented

•Studies: rudimentary information processing during sleep

•Habituation of EEG response, a simple form of learning occur during sleep eg certain brainwave reduce with repetitive irrelevant auditory stimuli,

•Stimuli attained meaning during waking state

•Appears that responds to simple meaningful stimuli may occur during sleep but not complex verbal material

•Learning associated with fast-wave sleep or alpha

•Minimal learning occurs in lighter sleep stages (stage 1 and 2)

Work schedule and sleep

•REM occur earlier in daytime sleep and stages 1 & 2 occur later compared to nighttime sleep

•Due to inversion of sleep- wakefulness cycle

•Compared to rotating shift work, permanent night workers show better adjustment of body temperature rhythm to night work and day sleep

•Sleep adjustment to night work helped by permanent night work

•Relate to danger of sleepiness in medical workers and detrimental consequences

Physical activity and sleep

•Afternoon exercise: cause increased slow wave sleep (SWS) during 1st half of night

•Same amount of morning exercise no influence sleep EEG

•Indicate rle of slow wave activity in recovery from work done later in day

•SWS: time when body repairs and restores

•Might be expected that SWS increase after exercise due to depletion of energy stores- not confirmed in research yet

Ageing and sleep

•Gradual age related changes in sleep occur

•REM sleep may remain unchanged but % of slow wave sleep reduces and time spent in stage 1 increases (men more affected)

•This shift toward lighter sleep contribute to increasings nighttime awakenings in elderly

•Average total sleep time also decline with ageing


Sleep deprivation

•Complete deprivation: 3-4 days max

•Partial deprivation or sleep restriction: impaired attention, reaction time, coordination and decision making

•selective deprivation: REM and SWS: rebound effect, study suggest REM and SWS important to firming up learning that occurs during awake (memory consolidation)

Sleep dep. And cognition

•Pilcher and Walters 1997: subject went 24hrs sleep deprivation prior to critical thinking assessment

•Performance of this group was lower than that of control group, who were not sleep deprived


Sleep disorders

•nsomnia- difficulty falling or stay asleep

•Narcolepsy: falling asleep uncontrollably, REM invasion into awake states

•Sleep apnea- reflexive gasping for air that awakens

•Nightmares- anxiety arousing dreams- REM

•Night terrors- intense arousal and panic- NREM

•Somnambilism- sleepwalking

•Sleep related movement disorders



•Refer to chronic problems in getting adequate sleep

•3 patterns: difficult falling asleep initially, difficult remain asleep, persistent early morning awakening

•Linked ot daytime fatigue, impaired functioning, increased risk of accident, reduced productivity, depression, increased health problems

•Cause: anxiety and tension, emotional problems eg. stress and depression, health problems such as back pain, ulcers, asthma and use of certain drugs eg. stimulants

Insomnia Treatment

•Sedative drugs eg. benzodiazepines: helps to fall asleep quicker, reduce night time awakening and increase total sleep

•Poor long term solution for insomnia: carryover effects (can make drowsy next day and impair functioning), can overdose with alcohol and opiate drugs, with continued use sedatives become less effective so people increase dose → lead to cycles of increasing dependency and daytime sluggishness

•newer generation of sedatives (eg. zolpidem) reduce some problems linked with traditional sleeping pills

•Can also use melatonin (functions as mild sedative) for insomnia, hormone used to treat jet lag


Periodic Limb movement disorder

•Characterised by repetitive movement of large toe with knee, ankle and hip flexion during sleep

•Can occur both legs, alternate or occur unilaterally

•Occur during light sleep (stages 1 & 2 of non REM sleep)

•incidence - equal in men and women and increases with age

•Can occur in 29% of person older than 50 years

•Around 80% of person with RLS also have PLMD

•Person may be unaware they have PLMD


Restless Leg syndrome

•Characteristics: urge to move limbs with or without sensations, worsening at rest, improving with activity, worsening in evening or night

•Conditions peaks in middle age and occur in 2-15% of elderly

•Origin: in CNS

•Can occur as primary or secondary disorder: high familial incidence of primary RLS, hence is genetic disorder, secondary cause include: iron deficiency, spinal cord, and peripheral nerve lesions, pregnancy, uremia (‘urine in the blood’- describes kidney failure) and medications

•CSF ferritin (main ion storage molecule in CNS) levels low in persons with RLS: iron play role in dopaminergic transmission in CNS, iron is important cofactor for tyrosine hydroxylase, the rate limiting enzyme in dopamine synthesis and play role in postsynaptic dopamine receptor function

•Diagnosis based on history of: compelling urge to move legs, motor restlessness (ie. tossing, turning in bed), symptoms that become worse at rest are relieved by activity (symptoms are worse in evening or night)

•Treatment- dopaminergic agents are 1st line of drugs:P dopamine precursors (carbidopa- levodopa), dopamine agonists (pergolide, pramipexole, ropinirole), facilitating agents (selegiline), antiseizure agents (gabapentin), benzodiazepines (clonazepam, temazepam), opioids ( codeine, hydrocodone) / Those with mild symptoms: muscle movement such as kicking, stretching or massage/ treatment of iron deficiency may improve symptoms


Sleep Apnea

•Reflexive gasping for air that can awaken person

•Sleep disordered breathing with excessive sleepiness during awake periods

•2 type: central sleep apnea (cause by disorder of respiratory center in brain, cessation or decrease in ventilatory effort during sleep and O2 desaturation, obstructive sleep apnea ( upper airway obstruction, snoring, disrupted sleep and excessive daytime sleepiness, although airflow ceases, respiratory muscles continues to function

Obstructive sleep Apnea

•Apnea is cessation of airflow through nose and mouth for 10 seconds or longer

•Apneic period last for 15-120 second and some can have as much as 100 apneic episode per night

•Reduction in tidal volume due to reduced depth and rate of respiration (hypopnea) associated with reduced arterial O2 saturation: apnea-hypopnea index- average number of apnea-hypopnea per hour

•Sleep related collapse of upper airway at pharynx level

•Loss muscle tone in upper airways cause airway obstruction as negative airway pressure produced by contraction of diaphragm bring vocal cord together, collapse pharyngeal wall and suck tongue back into throat

•Predisposition to sleep apnea: male, increasing age, obesity

•Large neck girth in male and female snorer is predictor of sleep apnea

•Gross motor movement during sleep

•More likely to fall asleep at inappropriate time which lead to accidents

•Associated with sleep related cardiac arrhythmias and hypertension (bradycardia observed also ventricular tachycardia in case of severe hypoxemia, frequency apneic period can result in high systemic and pulmonary BP)

•Diagnosis- sleep studies suggest sleep labs use polysomnography: EEG and EOG determine sleep stages, monitoring of airflow, ECG to detect arrhythmias, ventilatory effect measured, pulse oximetry to detect changes in oxygen saturation

Treatment of Obstructive Sleep Apnea

Treatment determined by severity of condition

•Mild SA: weight loss, eliminat evening alcohol and sedatives, proper bed positioning ( sleep in lateral position)

•Mild to moderate SA: oral or dental appliance that displace tongue forward and move mandible anteriorly. Side effects of devices: excessive salivation and temporomandibular joint discomfort

•Application of nasal continuous positive airway pressure (NCPAP) at night is helpful to treat apnea. Uses occlusive nasal mask or device that fit into nares, an expiratory valve and tubing and a blower system to generate positive pressure. Can cause dryness of mouth, claustrophobia and is noise

•Surgical procedure: nasal septoplasty (repair nasal septum), uvulopalatopharyngoplasty (excision of soft palate tissue, uvula and posterior pharyngeal wall_. Sever case may need tracheostomy (place tube into trachea for maintain open airways)