Sleep and Sleep Disorders Sleep and

							                        Sleep and Sleep Disorders
Learning Objectives
 By the end of this lecture the students should be able to:

     Understand the sleep physiology

     Describe the sleep types and various stages of sleep

     Analyze the brain wave forms during different staged of sleep

     Understand the effects of sleep deprivation

     Explain the sleep disorders

Stages of Sleep
     Stages of sleep are determined according to:

      – Brain waves: electroencephalogram (EEG)

      – Eye movements: electrooculogram (EOG)

      – Degree of muscle tension: electromyogram (EMG)

     Normal sleep is divided into two types:

          o Rapid Eye Movement Sleep (REM)

          o Non Rapid Eye Movement Sleep (NREM)

     NREM sleep is
      further divided
      into
      progressively
      deeper stages

          o Stage 1

          o Stage 2

          o Stage 3

          o Stage 4
NREM Sleep Stages
•Stage 1

– Light sleep: wakes very easily; floating feeling

– Rolling eye movements & relaxed muscles

•Stage 2

– Light sleep: wakes easily; daydreaming

– Eyes may roll, muscles relaxed

– Transition to REM occurs from this stage

•Stages 3 & 4

– Deep sleep, difficult to waken; realistic dreams, eneuresis, somnambulism & snoring

– No eye movement. muscles very relaxed

REM Sleep
Rapid eye movement sleep

– Difficult to awaken a REM-sleeper; may have sense of paralysis

– Characteristic rapid, eye movements give impression sleeper following something with gaze

– Muscle tone very low (except respiratory muscles); sporadic muscle twitching

Sleep Cycle
      Sleep progresses from stage 1 to 4; back through 3 & 2 before entering REM

      First REM sleep usually occurs 80-90 min after falling asleep; may last 3-4 min

      REM sleep tends to occur 5 times a night, each REM lasts longer with shorter intervals
       between

      If complete awakening occurs, sleep cycle begins again with stage 1

      If awakening very brief, may reenter at previous stage in cycle

Sleep Stages
      Stage 1 accounts for 2-5% of total sleep time

      Stage 2 represents 45-55% of total sleep time

      Stage 3 constitutes 5-15% of total sleep time

      REM represents 20-25% of total sleep time and occurs in 4-5 episodes throughout the
       night.

                                      Sleep Pattern




                            How much sleep is required
Some people like to sleep anywhere between 5 and 11 hours, with the average being 7.75 hours
Brain waves in different stages of sleep
       Stage         Frequency           Amplitude                  Waveform type
                        (Hz)            (micro Volts)

      awake             15-50                  <50


     pre-sleep          8-12                    50                    alpha rhythm

         1               4-8                  50-100                         Theta

         2              4-15                  50-150                 spindle waves

         3               2-4                  100-150        spindle waves and slow waves

         4              0.5-2                 100-200         slow waves and delta waves



       REM              15-30                  <50

Normal Sleep and Rest Patterns
• Sleep latency: period of time needed to fall asleep

• Sleep duration: length; 6 - 9 hrs is norm

• Position changes: 20 - 40/night is norm

• Night awakenings: 1 - 2, increases with age

• Circadian rhythms: biologic events occurring at 24 hr intervals such as:

– Sleep/wake cycle

– Body temperature fluctuations

– Hormone secretory cycle
Factors Affecting Sleep
     Nutrition: too little/too much food near bedtime

     Caffeine: long half life; can affect or delay sleep

     Alcohol: shortens sleep onset & rebound arousal

     Smoking: agitation; half life 1-2 hrs, smoking close to bedtime may delay sleep

     Exercise: activity increases REM & NREM sleep but if within 2 hrs of sleep can cause
      wakefulness

     Disruptions: schedule change, baby, phone etc

     Age-related issue

     Temperature: extremes impair sleep quality

     Light: problem in hospitals

     Noise: high noise levels assoc with less REM

     Sleep position: back sleepers have more apnea

     Pain: affects sleep latency and duration

     Medications: hypnotics, sedatives, anesthetics all decrease latency; cause wakefulness &
      anxiety

     Mood: depression & anxiety affect sleep
Sleep Deprivation
      Detrimental effects with loss of NREM/REM sleep

      < 6 hrs sleep/night affects coordination, reaction time & judgment.

      Can cause headache, anxiety, decreased pain threshold, GI upset, vertigo,irritability,
       delayed wound healing

      Can occur even if total sleep > 8 hours if frequent interruptions (will to stage 1 after each
       awakening)

      Awakenings in first 2 hrs causes NREM loss; later will cause REM loss

      Only 2/3 of lost REM sleep ever recovered

SLEEP DISORDERS
The most common sleep disorders include:

      Primary insomnia: Chronic difficulty in falling asleep and/or maintaining sleep when no
       other cause is found for these symptoms

      Bruxis m: Involuntarily grinding or clenching of the teeth while sleeping.
   Delayed sleep phase syndrome (DSPS): inability to awaken and fall asleep at socially
    acceptable times but no problem with sleep maintenance, a disorder of circadian rhythms.

   Hypopnea syndrome : Abnormally shallow breathing or slow respiratory rate while
    sleeping.

   Narcolepsy: Excessive daytime sleepiness (EDS) often culminating in falling asleep
    spontaneously but unwillingly at inappropriate times.

   Night terror: Pavor nocturnus, sleep terror disorder: abrupt awakening from sleep with
    behavior consistent with terror.

   Parasomnias: Disruptive sleep-related events involving inappropriate actions during
    sleep; sleep walking and night-terrors are examples

   Rapid eye movement behavior disorder (RBD): Acting out violent or dramatic dreams
    while in REM sleep.

    Obstructive sleep apnea: Obstruction of the airway during sleep, causing lack of
    sufficient deep sleep; often accompanied by snoring. Other forms of sleep apnea are less
    common

   Sleepwalking or somnambulism: Engaging in activities that are normally associated
    with wakefulness (such as eating or dressing), which may include walking, without the
    conscious knowledge of the subject.

   Nocturia: A frequent need to get up and go to the bathroom to urinate at night. It differs
    from Enuresis, or bed-wetting, in which the person does not arouse from sleep, but the
    bladder nevertheless empties.

   Somniphobia: a dread of sleep