Ch. 43 Sleep

Physiology of Sleep

  • Circadian rhythm

    • the 24-hour, day-night cycle

    • biological time clocks

  • Sleep regulation

    • homeostatic process (Process S)

      • regulates the length and depth of sleep

    • circadian rhythms (Process C)

      • influences the internal organization of sleep and the timing and duration of sleep-wake cycles

    • operate simultaneously to regulate sleep and wakefulness

    • Time of wake-up is defined by the intersection of Process S and Process C

  • Stages of sleep

    • Nonrapid eye movement (NREM) - 75% of night

    • Rapid eye movement (REM) - 25% of night

  • Sleep Cycle

    • Pre-sleep period: first 10-30 minutes

    • Three stages of NREM (N1, N2, N3) and REM sleep for a total of 90-110 minutes

    • The number of sleep cycles depends on the total amount of time that the person spends sleeping

Function of Sleep

  • A time of restoration, memory consolidation, and preparation for the next period of wakefulness

  • Sleep restores biological processes

    • Ex: during NREM stage 3 sleep, the body releases human growth hormone for the repair and renewal of epithelial and specialized cells such as brain cells

    • Protein synthesis and cell division for the renewal of tissues occurs

    • The basal metabolic rate lowers during sleep, which conserves the energy supply of the body

  • The benefits of sleep often go unnoticed until a person develops a problem resulting from sleep deprivation

  • Dreams

    • occur in NREM and REM sleep

      • the dreams of REM sleep are more vivid and elaborate

    • Important for learning, memory, and adaptation to stress

Normal Sleep Requirements and Patterns

  • The average daily amount of sleep needed, by age, is:

    • Newborns (up to 3 mos): 14 to 17 hours

    • Infants (4 to 12 mos): 12 to 16 hours, including naptime

    • Young children (1 to 5 yrs old): 10 to 14 hours, including naptime

    • School-aged children (6 to 12 yrs old): 9 to 12 hours

    • Teenagers (13 to 18 yrs old): 8 to 10 hours

    • Adults (18 yrs and up): 7 to 9 hours

Factors Influencing Sleep

  • Drugs and substances

  • Lifestyle

  • Usual sleep patterns

  • Emotional stress

  • Enviroment

  • Exercise and fatigue

  • Food and caloric intake

Sleep Assessment

  • Most people can provide a reasonably accurate estimate of their sleep patterns

  • Usually, patients are the best resource for describing sleep problems and how they are a change from their usual sleep and waking patterns

  • In addition, bed partners can provide information about patients’ sleep patterns that help reveal the nature of certain sleep disorders

    • sleep apnea, how frequently the apneic attacks occur

  • When caring for children, seek information about sleep patterns from parents or guardians

  • Questions to ask patient:

    • description of sleeping problems

    • usual sleep pattern

    • physical and psychological illness

    • current life events

    • emotional and mental status

    • bedtime routines

    • bedtime environment

    • behaviors of sleep deprivation