Normal sleep and sleep disorders

Normal sleep Awake state. Beta and alpha waves characterize the electroencephalogram (eeg) of the awake individual--- Beta waves over the frontal lobes are commonly seen with active mental concentration. Alpha waves over the occipital and parietal lobes are seen when a person relaxes with closed eyes.

Sleep state. During sleep, brain waves show distinctive changes -sleep is divided into rem (rapid eye movement) sleep and non rem sleep. non rem sleep consists of stages 123and4

Mapping the transitions from one stage of sleep to another during the night produces a structure known as sleep architecture Sleep architecture-changes with age .elderly have poor sleep quality because aging is associated with reduced rem sleep, delta sleep and total sleep time and increased night time awakenings

sedative agents –barbiturates & benzodiazepines ---reduced rem & delta sleep. Delta sleep occurs during first half sleep cycle. Longest rem periods occur during second half Average time for first rem period—90 mts.

Rem periods of 10-40 mts occur every 90 mts. throughout night Deprived rem sleep one night---has increased rem sleep next time rem rebound Extended rem deprivation---transient psychopathology---anxiety

Neurotransmitters are involved in the production of sleep. Rem ---commonly seen just before awakening Neurotransmitters are involved in the production of sleep. --increased levels of acetylcholine (ach) increase both total sleep time and rem sleep. Acetylcholine levels, total sleep time and rem sleep decrease in normal aging as well as in alzheimers disease.

Increased levels of dopamine decrease total sleep time Increased levels of dopamine decrease total sleep time . Treatment with antipsychotics, which block dopamine receptors, may improve sleep in patients with psychotic symptoms. Increased levels of norepinephrine decrease both total sleep time and rem sleep Increased levels of serotonin increase both total sleep time and delta sleep. Damage to the dorsal raphae nuclei, which produce serotonin , decreases both of these measures.

. Classification of sleep disorders --the diagnostic and statistical manual of mental disorders, 4th edition (dsm IV) classifies disorders in two major categories Dyssomnias are characterised by problems in the timing , quality, or amount of sleep .they include insomnia, hypersomnia, narcolepsy breathing related sleep disorder (sleep apnea ), circadian rhythm sleep disorder.

Parasomnias are characterized by abnormalities in physiology or in behavior associated with sleep. They include sleepwalking, sleep terror disorder and nightmare disorders. Insomnia, breathing related sleep disorder, and narcolepsy.

Insomnia Insomnia is difficulty falling asleep or staying asleep that occurs 3 times per week for at least 1 month and leads to sleepiness during the day or causes problems fulfilling social or occupational obligations. It is present in 30% of the population. --

Psychological causes of insomnia include the affective and anxiety disorders. --major depressive disorder ---characteristics of the sleep pattern in depression -normal sleep onset Repeated nighttime awakenings -waking too early in the morning (terminal insomnia) is the most common sleep characteristic of depressed patients.

Characteristics of the sleep stages in depression 1. short rem latency (appearance of rem within minutes of falling sleep) Increased rem early in the cycle and decrease rem later in the sleep cycle (i.e in the early morning hours) may lead to waking too early in the morning. 3. long first rem period and increased total rem 4.reduced delta sleep.

Bipolar disorder. Manic or hypomanic patients have trouble falling asleep and need less sleep. Anxious patients often have trouble falling asleep.

Physical causes of insomnia 1. use of central nervous system stimulants (e.g caffeine) is the most common cause of insomnia. 2. withdrawal of drugs with sedating action can result in wakefullness. 3. medical conditions causing pain also result in insomnia, as do endocrine and metabolic disorders

Breathing –related sleep disorder (sleep apnea) A. patients with sleep apnea stop breathing for brief intervals. Low oxygen or high carbon di oxide level in the blood awakens the patient repeatedly during the night, resulting in daytime sleepiness.

1. in patients with central sleep apnea (more common in the elderly), little or no respiratory effort occurs, resulting in less air reaching the lungs. 2. in patients with obstructive sleep apnea, respiratory effort occurs, but an air way obstruction prevents air from reaching the lungs. obstructive sleep apnea occurs most often in people 40-60 years of age, and is more common in men (8:1 male to female ratio) and in the obese (pickwickian syndrome) patients often snore.

Sleep apnea occurs in 1%-10% of the population and is related to depression, headaches, and pulmonary hypertension. It may also may result in sudden death during sleep in the elderly and in infants. .

Narcolepsy A. patients with narcolepsy have sleep attacks (ie fall asleep suddenly during the day) despite having a normal amount of sleep at night

B. narcolepsy is also characterized by 1. hypnagogic or hypnopompic hallucinations. These are strange perceptual experiences which occur just as the patient falls asleep or wakes up ,respectively, and occurs in 20-40%of patients. 2. short rem latency. 3. cataplexy. This is sudden physical collapse caused by loss of all muscle tone after a strong emotional stimulus & occurs in 70% of patients.

4. sleep paralysis—inability to move the body for a few seconds after waking, occurs in 30 – 50% of patients. Narcolepsy is uncommon. occurs in adolescent & young adults Treatment----