SLEEP

MODERATOR; DR DAPAP

DATE; 19^TH FEBRUARY,2024.

PRESENTERS

OUTLINE

• Introduction
• Normal Sleep Requirements
• Importance and Factors Affecting Sleep
• Sleep Cycle
• Sleep/Wake Switch, Sleep Process
• Sleep Wake Homeostasis
• Sleep Theory
• Types of Sleep
• Sleep Debt
• Effects of Sleep Deprivation
• Sleep Hygiene
• Clinic Assessment of Sleep and Diagnostic Testing
• Conclusion

INTRODUCTION �

• Sleep is an important part of our daily routine. It is estimated that we spend about a third of our time sleeping.

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• Quality sleep is just as important for good health as proper nutrition and physical activity.

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DEFINITION

• Sleep can be defined as “the natural periodic state of rest for mind and body with closed eyes characterized by partial or complete loss of consciousness”.

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Sleep is characterized by:

• low physical activity levels
• reduced sensory awareness
• Sleep is also regulated by the circadian rhythm and homeostatic mechanisms.

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Depth of sleep is not constant throughout. It varies in different stages of sleep.

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IMPORTANCE OF SLEEP

• (1)BIOLOGICAL FUNCTION :
• Muscle repair
• Cell repair
• Tissue growth
• Protein synthesis
• Release of many of the important hormones for growth

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• (2) COGNITIVE FUNCTION:
• Decision making
• Maintaining attention
• Recalling long term memories

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• (3) CONSERVATION OF ENERGY

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• (4) ADAPTATION

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NORMAL SLEEP REQUIREMENTS �

• Newborn: 16– 18 hours/day
• Infants: 12-14 hours/ day
• Toddlers : 10-12 hours/day
• Preschool: 11-12 hours/days
• School age: 8-12 hours/day
• Adolescents: 8-10 hours/day
• Adults: 6-8 hours/day
• Elders: 6 hours/day

FACTORS AFFECTING SLEEP CYCLE

• Both the quality and the quantity of sleep are affected by a number of factors.
• Sleep quality is a subjective characteristic while the quantity of sleep is the total time the individual sleeps

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FACTORS

1. Age
2. Illness e.g. back pain, sickle cell crisis
3. Environment: can promote or hinder sleep;

A. Noise

B. Temperature

C. Absence of usual stimuli or presence of unfamiliar stimuli can prevent people from sleeping.

D. Light levels

E. Sleep habits

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FACTORS

4.Lifestyle

5.Emotional stress

6.Stimulants and alcohol

7.Diet

8.Smoking

9.Motivation

10.Medications

SPECTRUM OF SLEEP AND WAKEFULNESS�

SLEEP CYCLE�

• The sleep cycle is an oscillation between the slow-wave and REM (paradoxical) phases of sleep.

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• It is sometimes called the ultradian sleep cycle, sleep–dream cycle, or REM-NREM cycle, to distinguish it from the circadian alternation between sleep and wakefulness.

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• In humans this cycle takes 1–2 hours.

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• The sleep–wake cycle as well as the various stages of sleep are due to the cyclic interplay of three different neural systems:
• Arousal system: regulated by a group of neurons in the hypothalamus and involves the reticular activating system originating in the brainstem
• A slow-wave sleep center: in the hypothalamus that contains sleep-on neurons that induce sleep
• A paradoxical sleep center in the brainstem that houses REM sleep-on neurons, which become very active during REM sleep.

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SLEEP/WAKE SWITCH

• The sleep/wake switch is regulated by

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• Orexin/hypocretin neurons in the lateral hypothalamus (LAT), which stabilize wakefulness, and by

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• The suprachiasmatic nucleus (SCN) of the hypothalamus, which is the body’s internal clock and is activated by melatonin, light, and activity to promote either sleep or wake.

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The arousal part consists of :�

• Basal forebrain and pontine areas contain acetylcholine neurons
• Locus coeruleus contain noradrenergic neurons
• Raphe nuclei contains serotonergic neurons
• Tuberomamillary nuclei contains histaminergic neurons

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• While the sleep state consists of
• Ventro-lateral Preoptic nucleus of hypothalamus

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SLEEP WAKE SWITCH

SLEEP PROCESS

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• Sleep occurs due to the activity of sleep inducing centres. Stimulation of these centres induces sleep.

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• Complex pathways between the reticular formation of brainstem, diencepahlon and cerebral cortex are involved in the onset and maintenance of sleep.

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• However, two centres which induce sleep are located in the brainstem; they are the Raphe nucleus and Locus ceruleus of Pons

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• The Raphe Nucleus is situated in the lower pons and medulla. Activation of this nucleus results in non-REM sleep. This is due to the release of serotonin by the nerve fibres arising from this nucleus. Serotonin induces non-REM sleep.

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• Activation of the Locus Ceruleus of Pons produces REM sleep. Noradrenaline released by the nerve fibres arising from locus ceruleus induces REM sleep.

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• The ascending reticular activating system (ARAS) is responsible for wakefulness because of its afferent and efferent connections with cerebral cortex. Inhibition of ARAS induces sleep. Lesion of the ARAS leads to a permanent somnolence i.e. coma.

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• More importantly, two internal biological mechanisms; circadian rhythm and homeostasis work together to regulate when you wake and when you sleep.

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CIRCADIAN RHYTHM�

• Circadian rhythms are internally driven cycles of biochemical, physiological and behavioural processes of living beings that rise and fall across the 24-hour day. Circadian regulation or Process C is controlled by the suprachiasmatic nucleus (SCN).

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• The circadian pacemaker in the suprachiasmatic nucleus has a direct neural connection to the pineal gland which releases the hormone melatonin at night.

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• The light/dark cycle of the sun is the strongest cue on circadian rhythms, encouraging wakefulness during the day and sleepiness at night. Exercise and melatonin also influence the pacemaker but not to the extent of light. Artificial light also influences the pacemaker.

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• The circadian pacemaker is most sensitive to light in the morning and the evening.

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• Blue light has the strongest impact on circadian rhythms. Exposing the eyes to blue light (or white light which includes blue light) during the sensitive periods trigger photoreceptors in the retina to send a signal to suppress melatonin and shift circadian rhythms.

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• Finally, body temperature has been associated as part of the circadian rhythm. The exact set point varies among different people, but it is expected to have generally lower temperatures in the morning and higher temperatures in the evening.

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• Process C counteracts the homeostatic drive for sleep during the day and augments it at night

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SLEEP-WAKE HOMEOSTASIS�

• Also known as Sleep Drive or Process S, homeostatic regulation is controlled by the hypothalamus. Although its exact nature is unknown, it is hypothesized that homeostatic pressure builds up during wakefulness and this continues until the person goes to sleep.

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• Process S is driven by the depletion of glycogen and the accumulation of adenosine in the forebrain that disinhibits the ventrolateral preoptic nucleus, allowing for inhibition of the ascending reticular activation system (ARAS).

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• Adenosine levels increase in the cortex and basal forebrain during prolonged wakefulness, and decrease during the sleep recovery period, potentially acting as a homeostatic regulator of sleep.

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• Coffee, tea and other sources of caffeine temporarily block the effect of adenosine, prolong sleep latency and reduce total sleep time and quality. In the same way, exercise can increase brain adenosine levels and through stimulation of adenosine receptors promote sleep.

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• Our body produces a higher drive for sleep under some circumstances. When the immune system is fighting an infection, it produces more immune mediators, which cause more sleepiness. Also cognitively stimulating or demanding experiences (such as sightseeing) and physically demanding experiences could increase sleep pressure further. As a result, sleep may be longer and deeper after those experiences.

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• Subjectively, however, humans seem to reach maximum sleepiness 30 hours after waking. Not getting adequate sleep causes a “sleep debt” to build up over time; sleep is needed to “pay down” this debt.

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• It is risky to build up a sleep debt and try to pay it off later. Although your level of sleepiness may return to normal after a day or two of recovery sleep, your neurocognitive performance can still be lower than baseline.

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SLEEP THEORIES

SLEEP THEORIES

Four theories are posited to explain the importance of sleep, they include;

• Inactivity theory
• Energy conservation theory
• Brain plasticity theory
• Restorative theory

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INACTIVITY THEORY

• Also known as the adaptive theory, it is based on the concept of evolutionary pressure where species sleep as an adaptive behaviour to protect against natural hazards and predators. Creatures inactive at night were less likely to die from the predation of injury in the dark, thus creating an evolutionary and reproductive benefit to being inactive at night.
• Similar to hunger and thirst, sleepiness may represent an underlying physiologic need which is only satisfied by sleeping and is integral to the survival of individuals. It is also suggested that our evolution at a faster rate as compared to other species is due to our focus on getting rest.

ENERGY CONSERVATION THEORY

• The energy conservation theory posits that the main function of sleep is to reduce a person’s energy demand during part of the day and night when it is least efficient to hunt for food. This theory is supported by the fact that the body has decreased metabolism by up to 10% during sleep. Body temperature and calorie demand drop during sleep and increase when we are awake, again supporting the hypothesis that sleeps plays an important role in helping to conserve energy resources.

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BRAIN PLACTICITY THEORY

• It says that sleep is necessary for neural reorganization and growth of the brain’s structure and function. It is clear that sleep plays a role in the development of the brain in infants and children and explains why infants must sleep upwards of 14 hours per day.
• It is important for cognitive function and memory formation. The quantity and quality of sleep has a major impact on learning and memory. This is because sleep helps in memory consolidation which is significant to learning whilst sleep deprivation affects focus and attention.

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RESTORATIVE THEORY�

• The restorative theory states that sleep allows for the body to repair and replete cellular components necessary for biological functions that become depleted throughout an awake day. This is backed by the findings that many functions in the body such as muscle repair, tissue growth, protein synthesis, and release of many of the important hormones for growth occur primarily during sleep.
• It is postulated that NREM sleep is important for restoring physiological functions and REM sleep is important in the restoration of mental functions.

TYPES OF SLEEP�

NON-RAPID EYE MOVEMENT SLEEP (NREM)�

• NREM sleep is classified into 3 stages
• Sleep episodes usually begin with a short period of NREM stage 1, progressing through stage 2, followed by stage 3, and finally to REM.
• NREM sleep constitutes about 75 to 80 percent of the total time spent in sleep.
• Irregular sleep cycles or absent sleep stages are associated with sleep disorders.
• The average length of the first NREM-REM cycle is 70 to 100 minutes.
• The second, and later cycles last longer, approximately 90 to 120 minutes.
• In normal adults, REM sleep increases as the night progresses, and is longest in the last one-third of the sleep episode.

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STAGE 1 SLEEP�

• The average individual’s sleep cycle starts from this stage.
• It usually lasts for 1 to 7 minutes in the initial cycle and constitutes 2 to 5 percent of total sleep.
• Easily interrupted by disruptive noises.
• There are slow and rolling eye movements.
• Heartbeat and breathing slow down.
• Muscles begin to relax.
• Brain activity on the EEG in stage 1 transitions from wakefulness (marked by rhythmic alpha waves) to low-voltage, mixed frequency waves.

STAGE 2 SLEEP

• Lasts approximately 10 to 25 minutes in the initial cycle, and increases with each successive cycle, eventually constituting between 45 to 55 percent of the total sleep episode.
• No eye movements
• Body temperature drops.
• An individual in stage 2 sleep requires more intense stimuli than in stage 1 to awaken.
• Brain activity on EEG shows relatively low-voltage, mixed-frequency activity, characterized by the presence of sleep spindles and K-complexes.

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STAGE 3 SLEEP

• Also known as slow wave sleep (SWS), or delta sleep.
• Arousal from this stage of sleep is difficult
• Heartbeat and breathing are at their slowest rate.
• No eye movements.
• The body is fully relaxed.
• Tissue repair, tissue growth and cell regeneration occur.
• Delta brain waves are present
• EEG shows high-voltage, slow-wave activity.

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RAPID EYE MOVEMENT (REM) SLEEP

• Characterized by presence of desynchronized (low-voltage, mixed frequency) brain wave activity, muscle atonia, and bursts of rapid eye movements.
• During the initial cycle, the REM period may last only 1 to 5 minutes; however, it becomes progressively prolonged as the sleep episode progresses.
• Dreaming is most often associated with REM sleep.
• Loss of muscle tone and reflexes prevents individuals from “acting out” their dreams or nightmares.
• Approximately 80 percent of vivid dream recall results after arousal from this stage

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RAPID EYE MOVEMENT (REM) SLEEP

• Two phases: phasic and tonic.
• Phasic REM sleep has rapid bursts of eye movements, tonic REM slep does not.
• Breathing and heart rate increase and become more variable.
• Muscles become paralyzed, but twitches occur.
• Brain activity is markedly increased

SLEEP DEBT

• Sleep debt, also known as sleep deficit, is when you sleep fewer hours than your body needs.
• It is cumulative. If you regularly get less sleep than you should, your sleep debt accumulates.
• The consequences of sleep debt include:
• Tiredness and depressed mood.
• Overeating and weight gain.
• Weaker immune system.
• Irritability.
• Wrinkled skin and dark circles.
• Memory problems.
• Slower reaction times.

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SLEEP DEBT

• To avoid the consequences of sleep debt, you should learn how much sleep your body needs and improve your sleep hygiene.
• Measures include:
• Know how much sleep you need.
• Keep a sleep dairy.
• Develop a nighttime routine.
• Reconsider your daytime schedule.
• Avoid caffeine after sunset.
• Make your bedroom more sleep-friendly.
• Exercise during the day.

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SLEEP DEPRIVATION

• Sleep deprivation happens when a person does not get the sleep they need to sustain their health and well-being. It is common for people to sacrifice sleep for work, school, or fun, but even one night of inadequate sleep can leave people feeling tired, less productive, and more prone to mistakes the next day.
• As sleep debt grows over time, it begins to take a toll on mental and physical health. Long-term sleep deprivation can reduce quality of life and may increase the risk of health issues including obesity, diabetes, and cardiovascular disease.

CAUSES OF SLEEP DEPRIVATION

• There are many potential causes of sleep deprivation, ranging from natural changes in the body as people age to an undiagnosed medical condition or sleep disorder.
• In teens, sleep deprivation can develop because of changes during puberty that lead adolescents to prefer later bedtimes. This natural preference for late nights often conflicts with early morning school schedules, making it difficult for teens to get the sleep they need.
• In women and people assigned female at birth, sleep loss can occur at certain times during their menstrual cycle. People commonly have fragmented sleep in the week before their period begins . Sleep loss is also common during and after pregnancy and during menopause.

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• Other causes of sleep deprivation include poor sleep habits, busy schedules, and health issues that interfere with getting enough quality rest.
• Medical conditions: Many medical problems can interfere with sleep, including pain, heart failure, and asthma. Some medical conditions may flare up or get worse at night, like acid reflux or chronic obstructive pulmonary disease (COPD).
• Medications and substances: A wide variety of medications can interrupt sleep or make it more challenging to doze off. These include certain steroids, decongestants, pain medications, and drugs used to treat anxiety and depression.
• Mental health conditions: Several mental health conditions are linked to sleep challenges, including depression, anxiety, and bipolar disorder, as well as attention deficit hyperactivity disorder (ADHD) , and autism spectrum disorder.

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WHAT ARE THE EFFECTS OF SLEEP DEPRIVATION?

• Research has found that sleep deprivation affects systems throughout the body, leading to a wide range of negative effects.
• Daytime sleepiness: Not getting enough sleep is a common cause of people feeling tired during the day . Daytime sleepiness can leave a person without the energy to do the things they enjoy and cause problems at work, school, and in relationships.
• Impaired mental function: One of the most noticeable effects of sleep loss is cognitive impairment. As sleep debt grows , a person becomes less alert and may have difficulty multitasking. Reductions in attention make a sleep-deprived person more prone to mistakes, increasing the risk of a workplace or motor vehicle accident.

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• Mood changes: Sleep loss can lead to mood changes and make a person feel more anxious or depressed. Without enough sleep, people may feel irritable, frustrated, and unmotivated. They may also struggle to deal with change and to regulate their emotions.
• Reduced immune function: Sleep is important for maintaining a healthy immune system, so sleep deprivation can weaken immune function.
• Weight gain: Sleep is important for maintaining a healthy weight . Not getting enough sleep can affect appetite and metabolism in ways that can lead to weight gain. Insufficient sleep has been associated with an increased risk of obesity.

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• Diabetes: A lack of sleep can make it more difficult for the body to process sugar, contributing to glucose intolerance and increasing the risk of type 2 diabetes. 
• Heart disease: During normal sleep, blood pressure drops in ways that are believed to support heart health. Sleep deprivation prevents this drop in blood pressure and triggers inflammation, heightening the risk of cardiovascular diseases, such as heart disease and stroke. 
• Mental health conditions: Sleep deprivation is closely linked to mental health . Sleep loss may increase the risk of mental health issues, and those issues can make it harder to get enough sleep

SYMPTOMS OF SLEEP DEPRIVATION

• Waking up feeling unrefreshed 
• Daytime sleepiness 
• Falling asleep unexpectedly during the day 
• Difficulty functioning at home, work, or school 
• Trouble concentrating and slow reaction times 
• Mood changes and problems controlling emotions 
• Spending more than 30 minutes trying to fall asleep
• Feeling tiredness in the morning despite a full night of sleep 
• Waking up frequently during the night 
• Snoring loudly or gasping for air while sleeping 

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PREVENTING SLEEP ISSUES( SLEEP HYGIENE)

To reduce the risk of sleep deprivation, it is important to take steps to improve sleep hygiene. 

• Make sleep a priority: Prioritize sleep health by creating a comfortable sleep environment and keeping a consistent sleep schedule. This means going to sleep and waking up at around the same time each day and avoiding the temptation to stay up later or sleep in on the weekends.
• Combat stress: To combat bedtime stress, give yourself plenty of time to wind down from the day. Use this time to listen to calming music, stretch, or write in a journal.
• Time your light exposure: Ambient light can signal to the body whether it is time to be awake or prepare for sleep, so be intentional about light exposure. Try to get at least 30 minutes of sunlight exposure during the day and then dim or turn off lights in the evening. Shut off phones, TVs, and computers at least an hour before bed.

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• Watch your caffeine intake: Caffeine can linger in the body for eight or more hours, so consuming caffeine in the afternoon may affect how long it takes to doze off at bedtime.
• Nap wisely: Although they cannot replace quality nighttime rest, naps can be a helpful tool to improve daytime alertness. If naps are too long or poorly timed, though, they can make it more difficult to fall asleep in the evening.
• Stay active: Regular exercise can make it easier to get to sleep at bedtime. Try to get at least 30 minutes of physical activity every day, but it is best to avoid highly strenuous exercise too close to bedtime. 

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SLEEP ASSESSMENT

HISTORY TAKING

• When assessing sleep, sleep history should be evaluated including total amount of sleep, usual sleep patterns, quality of sleep, use of sleeping aids like alcohol, sedatives, or hypnotics.

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• Psychiatric and medical history e.g anxiety, respiratory symptoms,etc.

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• Evaluations of current medications

DIAGNOSTIC TESTS

• Sleep Diary: It is a daily record of important sleep related information. It is more subjective and cheaper.
• Actigraphy : This test uses a special device worn on the wrist to monitor movement, including sleep. Actigraphy is often recommended when doctors are trying to identify a sleep problem because it offers more objective data than a sleep diary. 

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• Sleep Study e.g polysomnography, titration study,multiple latency tests.

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• Polysomnography(PSG): This is a type of sleep study which includes at least 3 independent tests (EEG, EOG, EMG) that monitor different body functions during sleep (Luyster et al., 2015). This is the gold standard test.

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SLEEP ASSESSMENT ; POLYSOMNOGRAM

• Electroencephalogram (EEG)—measures and records the brainwave activity to identify sleep stages and seizure activity.

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• Electrooculogram (EOG)—records eye movements. These movements are important for identifying the various sleep stages, especially the REM stage.

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• Electromyogram (EMG)—records muscle activity such as teeth grinding and face twitches

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WHY A SLEEP ASSESSMENT?�

This could help in the diagnosis of some certain disorders like:

• Sleep apnea
• Narcolepsy
• Periodic limb movement disorder
• REM sleep behavior disorder
• Unexplained long lasting insomnia

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CONCLUSION

• Sleep is an investment in the energy you need to be effective tomorrow.

REFERENCES

• 4 Stages of Sleep: NREM, REM, and the Sleep Cycle https://www.verywellhealth.com/the-four-stages-of-sleep-2795920
• Bestha, C. M. (2018). Sleep Cycle[PowerPoint slides]. SlideShare. https://www.slideshare.net/pulsar7066/sleep-cycle-119093303
• EEG sleep stages, illustration - Stock Image - C051Science https://www.sciencephoto.com/media/1158883/view/eeg-sleep-stages-illustration
• Feng CC., Bertiz R., Agostini M.; Focused Assessment: Sleep Assessment; https://oer.pressbooks.pub/healthassessment.montgomerycollege/chapter/focused-assessment-sleep-assessment/#:~:text=The%20sleep%20study%20is%20a,cycles%
• 20with%20an%20EEG%20monitor.
• Humaira, K. (2015). Sleep[PowerPoint slides]. SlideShare. https://www.slideshare.net/zaryabghauri/sleep-54821145?qid=486e0680-522e-44de-916a-a9911bf03c4f&v=&b=&from_search=8

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