Sleep and Sleep Disorders

Neural Control of Sleep  Sleep and waking are different states of arousal.  Reticular activating system controls this.  Decrease in arousal is accompanied by less cortical activity.

Neural Control of Sleep  Bodily cycles (circadian rhythms) are controlled by part of the hypo- thalamus.  Pineal gland controls circulating levels of melatonin— more light, less melatonin.

Biological Clock Circadian Rhythms

Stages of Sleep REM Sleep

Rapid Eye Movement (REM)Sleep  Eyes move rapidly.  If awakened 90% report dreaming.  Paradoxical  Muscles relaxed.  Brain active.  Sometimes called active sleep.  Seems to be necessary.  If insufficient, amount per night increases.

Effects of REM Deprivation

Sleep Disorders

Sleep Apnea  Most who suffer from sleep apnea snore heavily.  All snorers do not have sleep apnea.  So what is it?

Sleep Apnea  Relaxation of sleep leads to blocking of airway.  Person awakes briefly, gasps, and falls back to sleep.  May happen 100s of times per night.

Insomnia  Inadequate or poor quality sleep because of:  Difficulty falling asleep.  Waking up frequently during the night with difficulty returning to sleep.  Waking too early in the morning.  Unrefreshing sleep.

Insomnia  More common for:  Elderly  Females  Those who are depressed.  Causes:  Stress  Environmental noise  Extreme temperatures  Change in the surrounding environment  Sleep-wake schedule problems, e.g., shift work, jet lag.  Side effects of medication.

Insomnia  Contributing factors:  Expecting to have difficulty sleeping.  Large amounts of caffeine.  Drinking alcohol before bedtime.  Smoking cigarettes before bedtime.  Excessive napping in the afternoon or evening.  Irregular, or continually changing sleep-wake schedules.

Less Common Sleep Disorders  Narcolepsy  Sleep disorder characterized by sudden bouts of irrepressible sleep.  Individual may fall to ground in sound sleep.  Can be dangerous if not controlled.  Regular hours and sufficient sleep.  Drugs  Cataplexy  Individual experiences sudden muscle paralysis as in REM sleep while they are awake.  Will collapse.

Sleep Walking  More common in children.  Usually outgrown by the age of 15.  Occurs during deepest sleep rather than REM sleep.

Night Terrors

 Also occurs during deepest, Stage 4 sleep.  Most common in children between 4 – 7 years of age.  Child wakes crying as if in terror but seems as if not really awake. No response to visual stimuli or questions.  May, or may not report a scary dream when fully awake.

What is Sleep For?  It seems to be restorative:  Restores glycogen stores and stengthens the immune system.  Bodily repair—extremely active people sleep more.  Bodily rhythms may have evolved to ensure quiet periods during time when most predators for the species are about.  Consolidation of learning:  Lack of sleep interferes with memory storage.