Understanding Sleep Stages and Benefits

Sleep Introduction

• The session focuses on the importance of sleep.

Agenda

• Explores the three stages of sleep.
• Discusses how to apply good sleep habits.
• Details the health benefits of sleep and the consequences of disrupted sleep.
• Describes the need for sleep through the lifespan.
• Outlines common sleep disorders and their treatments.

NREM Sleep

• The first three stages of sleep are grouped as non-rapid eye movement (NREM) sleep.
• NREM sleep improves neural connections and helps with cell restoration and repair.

Stage 1 Sleep

• A short, transitional phase from wakefulness to sleep.
• A person is easily disturbed by outside stimuli during this stage.
• Individuals may not realize they have fallen asleep.
• People are sleeping but can still hear outdoor activity.

Stage 2 Sleep

• Deeper than stage 1 but still a light sleep.
• Heart rate slows and body temperature drops.
• Bursts of brain activity occur, including sleep spindles and K-complexes.
• Stimuli from the environment can no longer reach higher-level brain centers.
• Taking a lot to wake someone up is common such as CO2 detectors beeping loudly.

Stage 3 Sleep

• This is the deepest sleep stage and is the most important for restorative functions.
• Supports the most restorative functions.
• The length of stage 3 increases after physical activity or extended periods of no sleep.
• Difficult to wake up quickly and may be confused.
• Memory and learning can become active during stages II and III.
• All that you have studied throughout the day downloads for memory creation

REM Sleep

• The final stage of sleep.
• Named for the rapid eye movements that occur under the lids.
• Most dreaming occurs during this stage.
• Some brain regions become more active.
• Blood pressure, respiration, and heart rate rise, while skeletal muscles are inhibited from contracting.
• This is known as dream sleep.

EEG Patterns

• EEG (electroencephalogram) patterns change with each sleep stage.

Sleep Cycles

• The first cycle involves the three stages of NREM sleep.
• Followed by a period of REM sleep, which is always the final stage.
• A full sequence lasts about 90 minutes and may go through four to five cycles.
• Slow-wave sleep is longer in the first part of the night.
• More REM sleep occurs in the latter part of the night, during dreaming.

Natural Sleep Drives: Circadian Rhythm

• A sleep-wake pattern coordinated by the suprachiasmatic nucleus (SCN).
• Every cell has a sleep-wake pattern dictated by DNA, and the SCN coordinates them all.
• Night is the circadian rest phase.
• Insufficient sleep disrupts repair and regeneration tasks.

Natural Sleep Drives: Circadian Rhythm Variation

• Genetics determine if someone is an early riser or a night owl.
• Morning people do better in the day but tire earlier, making them more sensitive to sleep loss.
• Evening people perform better in the evening and handle sleep loss more effectively.

Natural Sleep Drives: Circadian Rhythm disruptions

• Jet lag occurs when the internal clock is set to a new environment.
• This results in falling asleep and waking at inappropriate times
• Jet lag can cause nausea and loss of appetite.
• Delayed sleep phase occurs when a person stays up until 4 AM and sleeps until noon, making it difficult to wake up earlier.

Natural Sleep Drives: Homeostatic Sleep Drive

• Pressure to sleep is related to the amount of prior wakefulness.
• The circadian rhythm works in opposition to the homeostatic drive.
• Homeostatic drive is thought to be mediated by the neurochemical adenosine.
• More time spent awake leads to more adenosine, which promotes sleepiness.
• Sleep clears adenosine from the brain.

Natural Sleep Drives: Light

• Light has a direct connection to the suprachiasmatic nucleus (SCN) via the eye.
• Exposure to light in the morning at a certain time regularly causes the SCN to set the internal clock to wake up at the same time.
• Light can also reinforce unhealthy behavior.
• Light exposure late at night resets the SCN, delaying the sleep phase.
• The SCN also causes the pineal gland to secrete melatonin at dusk, preparing the body for sleep.
• Blind persons often have a difficult time with sleep due to the lack of light stimulation.
• Unnatural light sources undermine reliance on the sun’s 24-hour cycle.
• Blue light produced by electronics is most disruptive and can affect life.

Sleep Recommendations for Canadians

• Infants (0-3 months): 14-17 hours
• Infants (4-11 months): 12-16 hours of good quality sleep, including naps
• Toddlers (1-2 years): 11-14 hours of good quality sleep, including naps, with a consistent bedtime and waking-up time
• Preschoolers (3-4 years): 10-13 hours of good quality sleep, including naps, with a consistent bedtime and waking-up time
• Children (5-13 years): 9-11 hours of uninterrupted sleep
• Teens (14-17 years): 8-10 hours with a consistent bedtime and waking-up time
• Adults (18-64 years): 7-9 hours of good quality sleep consistently, with a consistent bedtime and waking-up time
• Seniors (65+ years): 7-8 hours of good quality sleep consistently, with a consistent bedtime and waking-up time

Changes in Circadian Rhythm Across the Lifespan

• The most prominent changes across the lifespan are circadian rhythm changes.
• Children need to go to bed earlier than adults.
• Insufficient sleep can interfere with attention and learning.
• Adolescents tend to stay awake at night and sleep late in the morning.

Impact of Sleep on Students

• Sufficient sleep aids in positively affecting grades and moods.
• High school and post-secondary students show a sleep deficit of 1-3 hours on school nights.
• Many students sleep longer on weekends to compensate.
• Almost 2/3 of students are getting poor sleep.
• School start times force students to rise during their biological night, resulting in serious sleep deprivation.
• Sleep is important for higher-order thinking, problem-solving, reasoning, and good judgement.
• School districts with later start times found a decrease in tardiness, absences, drop-out rates, school nurse visits, and car accidents.
• Circadian rhythms shift away from the `night owl' tendency
• A study shows there may be a substantial economic gain by delaying school start times.

Sleep Cycles, Age and Sex

• As people age, the duration and quality of sleep tends to decrease.
• Children tend to be the hardest to rouse because their slow-wave sleep and greater threshold for transition from sleep to wakefulness.
• By late 40s, 60-70% of deep sleep is gone, and by age 70, it decreases by 80-90%.
• Women tend to show less sleep disruption than men.
• As we get older, we wake up more easily
• Experience a lighter stage of sleep and become more sensitive to external stimuli.
• Age reduces time in restorative sleep, amplitude and intensity of deep-sleep brainwaves
• Women report more instances of insomnia and men report more snoring
• Women may have sleep disruption due to menstruation, menopause or pregnancy
• May be linked to nerodegeneration and sleep apnea
• Fully waking up takes 45 minutes

Sleep Disorders: Chronic Insomnia

• Insomnia is a condition where people have difficulty falling or staying asleep.
• Approximately 30% of North American adults have some symptoms of insomnia.
• People with no circadian rhythm issues generally do not feel sleepy in the daytime.
• Symptoms for insomnia occur not only at night but in daytime hours
• Insomnia is considered chronic if sleep disruption occurs at least three nights per week over a three-month period.

Chronic Insomnia Treatment

• Treatment relies on addressing sleep disruptors or circadian rhythm factors.
• Should discover the cause of poor sleep for remedies such as coughing, urination, anxiety, reflux, and congestion
• Sleeping pills are not recommended.
• It is important to shorten the sleep period slightly and set a strict sleep window by going to bed at the same time every night.
• Sleep restriction or consolidation approaches are very effective.
• Daytime naps need to be limited
• No biological benefits of oversleeping

Environmental Factors for Insomnia Treatment

• Must create a healthy sleep environment
• Only use bed for sleeping
• Exercise daily, but not close to bedtime
• Avoid screen-based technology to limit exposure to blue light

Professional Help for Insomnia Treatment

• See a physician for referral to a sleep specialist.
• May be a candidate for a sleep study.

Sleep Disorders: Restless Leg Syndrome (RLS)

• RLS symptoms include a crawling feeling under the skin, an ache, or tingling sensation.
• Symptoms happen more in the evening.
• It can be alleviated by walking around or moving the legs.
• RLS can be associated with small kicking movements during the night.

RLS Treatment Recommendations

• Get more exercise during the day.
• Avoid all caffeine and ensure iron levels are in the middle range.
• OTC meds like Benedryl® may worsen sleep.

Sleep Disorders: Sleep Apnea

• Sleep apnea is caused by a narrowed airway that gets more obstructed while sleeping.
• Sleep apnea is associated with hypertension, heart attacks, and stroke.
• Also has a negative impact on diabetes.
• There is an increase in work-related + motor vehicle accidents
• Most common in overweight persons.
• Loud snoring and a family history can be indicators of possible sleep apnea.

Sleep Apnea Treatment Recommendations

• Can have a major impact on quality of life.
• Lifestyle changes include weight loss, sleeping on your side, and quitting smoking while using medications to keep nasal passages open at night.
• Dental devices or continuous positive airway pressure (CPCP) masks and machines are available.
• Surgical treatment may include the removal of tonsils or adenoids.

Sleep Disorders: Narcolepsy

• Narcolepsy symptoms include feeling sleepy during the daytime and the urge to sleep at inappropriate times.
• People with narcolepsy will often not sleep well at night.
• There is a transition from sleep to waking where the REM paralysis lingers.
• Cataplexy is also a symptom, which is characterized by a sudden loss of muscle control.
• Can be triggered by strong emotion, laughing hard, or getting startled.

Narcolepsy Treatment Recommendations

• Treatment options are few and ineffective.
• Modafinil helps afflicted people stay awake during the day.
• Antidepressants suppress REM sleep and the paralysis effects.
• Treatment is contraindicated in pregnant women.

Mood and Depression

• Sleeping difficulty is often reported in those struggling with depression or mood disorders.
• There is a risk for depression that rises with insomnia.
• Treating sleep problems also improves depression.
• Neurochemical changes make people more vulnerable to depression.

Sleep Deprivation

• A night of poor sleep can make people irritable the next day.
• Can affect emotions, making people more volatile and disinhibited.
• In adolescents, more risk-taking behavior is noted when sleep-deprived.
• Sleep problems are correlated with suicides, especially among young adults.
• There is an association between insomnia and suicidal thoughts.
• Being aware of the connections between mood and sleep can contribute to better mental health.

Dementia

• Dementia is a major disease that often comes with age.
• Approximately 20% of older adults develop memory problems.
• Sleep may prevent cognitive impairment and dementia.
• Changes occur in the fluid surrounding the brain during sleep.
• This leads to a flow of cerebral spinal fluid (CSF) that increases by 90%.
• CSF allows for the waste products of nerve metabolism to clear.
• Proteins such as amyloids have been associated with Alzheimer's disease.
• The glymphatic system helps clear waste from the brain.
• Sleep disruption at night increases the risk of dementia or causes it to develop earlier.

Athletic Performance

• Sleep can have a profound effect on athletic performance.
• Student athletes perform better in their sports and in the classroom by adhering to a more rigid sleep schedule.
• Circadian rhythms are also important and is affected crossing time zones, longer flights increases jet lag in players
• East coast teams playing west coast teams were most adversely affected
• Growth hormones are also affected with sleep loss, growth hormone and, testosterone are released during sleep – levels are reduced with sleep loss, testosterone is necessary for muscle health therefore sleep is necessary for optimal performance.

Musculoskeletal Pain

• Poor sleep can lead to a risk of developing body pain and reducing pain threshold.
• Improving a patient's sleep can improve pain symptoms.
• A challenge is that pain may interfere with the sleep process.
• Creates a feedback loop.

Obesity and Weight Management

• Ghrelin and leptin are affected by sleep.
• When there is a lack of sleep, people eat more and gain more weight.
• Ghrelin rises when we have not eaten, increasing appetite.
• Leptin rises after we eat and makes us feel “full”.
• Sleep deprivation causes leptin levels to fall by 20-30%, while ghrelin increases by the same amount.
• Reward centers in the brain are activated by food stimuli when sleep-deprived.
• Leads to increased sugar and fat intake
• Become more fatigued, leading to being sedentary, leading to weight gain.

Cardiovascular Disease

• The strongest connection is sleep apnea, particularly in people who snore.
• Also have hypertension – 2 to 3 times the risk.
• Hypertension is related to other cardiac disorders.
• Which includes cardiac arrest, strokes and coronary heart disease
• Sleep apnea can promote inflammatory pathways contributing to plaque in the arteries.
• Cardiac arrhythmias such as atrial fibrillation can be promoted by sleep apnea.
• In males, a sleep duration of less than 6 hours can lead to an increased risk of mortality.
• If hypertensive, the risk increases.
• It is recommended that sleep medications should not be used, as there is an association with a higher mortality risk.

Diabetes

• Sleep can affect the risk of developing diabetes.
• In males with short sleep duration, the risk of developing type II diabetes rose two-fold.
• People with problems falling asleep have a 50% chance of developing diabetes.
• Untreated sleep apnea is associated with glucose regulation problems.
• The ability of insulin to regulate glucose was impaired in young people when slow-wave sleep was disrupted.

Public Health Impact: Auto Accidents

• Driving while tired is the same as impaired driving.
• Being awake for 17 to 19 hours is equivalent to having a blood alcohol content of 0.05%.
• Symptoms of fatigue can result in a driver being unable to react to a situation on the road.
• Charges can vary in severity from distracted driving to criminal negligence.
• Do not get behind the wheel without enough sleep
• Errors match people who are legally drunk
• Combination of alcohol and sleep deprivation are exponentially lethal
• Momentary lapses in concentration can last a few seconds
• The brain losses perception of your surround

Public Health Impact: Microsleep

• A momentary lapse in concentration.
• Can last a few seconds
• Just long enough to lose control.
• The brain losses perception of the outside word
• You do not know you have had a microsleep.
• Occurs most often when getting less than seven hours of sleep.
• Such a risk affects parents with small children (infants).
• Shift workers.
• Those who leave sleep disorders untreated
• Peak period is from 4 am to 6 am.

Public Health Impact: Sleepiness Prevention

• One should ensure adequate sleep.
• If feeling drowsy during driving, pull over.
• One should prepare for an anticipated period of sleep deprivation by scheduled napping.

Public Health Impact: Workplace

• Workplace accidents have been attributed to human error related to sleepiness
• Theses include; 1989 Exxon Valdez oil spill, 1986 Chernobyl nuclear disaster, 1986 Challenger space shuttle disaster, 1979 Three-mile island nuclear disaster.