Sleep Stages, Disorders And Seizurs

SLEEP Stages, Disorders And Seizures By Hassan Mohammad Al-Shehri ID#2051040006

EEG Changing During Wakefulness-Cycle: The EEG has allowed us to understand better the activity of the brain in both awake and sleep states.

Sleep Stages: Waking through Stage 2 When we are awake, we are in one of two states according to the EEG: 1- a relaxed mental state (alpha waves) or 2- alert mental state (beta waves). When we are asleep, we enter into several different states including theta and delta waves which are much slower than those in the awake state. The First stage of sleep is characterized by theta waves, which are slower in frequency and greater in amplitude than alpha waves. The difference between relaxation and stage 1 sleep is gradual and subtle. As the sleeper moves to stage 2 sleep theta wave activity continues, interspersed with two unusual wave phenomena. These phenomena, which occur periodically every minute or so, and are defining characteristics of stage 2 sleep, are termed sleep spindles and K complexes.

The former is a sudden increase in wave frequency, and the latter is a sudden increase in wave amplitude. Stages 1 and 2 are relatively "light" stages of sleep. In fact, if someone is awoken during one of these stages, he or she will often report no being asleep at all.

Sleep Stages: Delta Sleep and the Sleep Cycle During a normal nights sleep a sleeper passes from the theta waves of stage 1 and 2, to the delta waves of stage 3 and 4. Delta waves are the slowest and highest amplitude brain waves. There is no real division between stages 3 and 4 except that, typically, stage 3 is considered delta sleep in which less than 50 percent of the waves are delta waves, and in stage 4 more than 50 percent of the waves are delta waves. Delta sleep is our deepest sleep, the point when our brain waves are least like waking. Consequently, it is most difficult stage in which to wake sleepers, and when they are awakened they are usually sleepy and disoriented. Delta sleep is when sleep walking and sleep talking is most likely to occur. In a normal night's sleep, a sleeper begins in stage 1, moves down through the stages, to stage 4, then back up through the stages, with the exception that stage 1 is replaced by REM (characterized by rapid eye movement and sudden and dramatic loss of muscle tone), then the sleeper goes back down through the stages again. One cycle, from stage 1 to REM takes approximately ninety minutes. This cycle is repeated throughout the night, with the length of REM periods increasing, and the length of delta sleep decreasing, until during the last few cycles there is no delta sleep at all.

Sleeping disorders: 1- Insomnia Not sleeping enough due to: (1) Difficulty in falling asleep (onset insomnia), (2) Frequent awakening during sleep (maintenance insomnia), or, (3) Waking up too early (termination insomnia). Can be caused by noise, temperature, stress, diet, medications, and some psychiatric or neurological disorders (e.g., epilepsy, Parkinson's, depression, anxiety) May be related to shifts in circadian rhythms

2- Narcolepsy frequent, unexpected periods of sleep or sleepiness during the day. Includes one or more of these symptoms: 1. Gradual/sudden onset of sleepiness 2. Cataplexy: muscle weakness while remaining awake. Often triggered by strong emotions 3. Sleep paralysis: inability to move when falling asleep or waking up 4. Hypnagogic hallucinations: dreamlike experiences at the beginning of sleep. Cause : Is unknown. Possibly due to •

Overactive ACh synapses in the pons which send messages to spinal cord, or,

•

Axons using the neurotransmitter orexin (hypocretin) in the hypothalamus connect to areas which increase arousal & wakefulness. Humans with narcolepsy do not have these cells in the hypothalamus (perhaps due to an autoimmune disorder).

Treatment : with stimulants, e.g., Ritalin or Cylert

3- Sleep apnea intermittent stopping of breathing during sleep due to obstruction of the airway or central nervous system problems Often caused by obesity, hormonal imbalances, or genetics.

4- Sleepwalking (also called Noctambulism or Somnambulism) Sleepwalking can affect people of any age. It generally occurs when an individual awakes suddenly from Slow Wave Sleep. causing the sleepwalking episode. In children and young adults, up to 25% of the night is spent in SWS. However this decreases as the person ages until none can be measured in the geriatric individual.For this reason, children and young adults (or anyone else with a high amount of SWS), are more likely to be woken up and, for the same reasons, they are witnessed to have many more episodes than the older individuals. Treatment : No treatment other than making sure that the person's environment is safe.

5- Bedwetting (or Nocturnal Enuresis or Sleep Wetting) is involuntary passing of urine while asleep after the age at which bladder control would normally be anticipated. Causes: (1) Infection/Disease: Less than 5% of all bedwetting cases. (2) Genetics: Bedwetting has a strong genetic component. Children whose parents were not enuretic have only a 15% incidence of bedwetting. When one or both parents were bedwetters, the rates jump to 44% and 77% respectively. (3) Physical Abnormalities: Less than 10% of enuretics have urinary tract abnormalities, such as a smaller than normal bladder. (4) Insufficient Anti-Diuretic Hormone (ADH) Production: A portion of bedwetting children do not product enough of the Anti-Diuretic Hormone. Normally ADH increases at night. (5) Stress: Stress is controversial as a possible cause of bedwetting. (6) Psychological: In rare cases, bedwetting is a symptom of a more severe underlying psychological problem. (7) Caffeine: Caffeine increases urine production. (8) Constipation: Chronic constipation can cause bedwetting. When the bowels are full, it can put pressure on the bladder.

Seizure Types and their EEG Pattern: Different types of seizure may have different causes, prognosis and treatments. Based on the type of behavior and brain activity, seizures are divided into two broad categories: generalized and partial (also called local or focal). Classifying the type of seizure helps physicians diagnose whether or not a patient has epilepsy. Generalized seizures are produced by electrical impulses from throughout the entire brain, whereas partial seizures are produced (at least initially) by electrical impulses in a relatively small part of the brain. The part of the brain generating the seizures is sometimes called the focus. The most common types of seizures are listed below: Generalized Seizures (Produced by the entire brain)

Symptoms

1. "Grand Mal" or Generalized tonic-clonic

Unconsciousness, convulsions, muscle rigidity

2. Absence

Brief loss of consciousness

3. Myoclonic

Sporadic (isolated), jerking movements

4. Clonic

Repetitive, jerking movements

5. Tonic

Muscle stiffness, rigidity

6. Atonic

Loss of muscle tone

Partial seizures can be further characterized as simple (not affecting awareness and memory) or complex (affecting awareness and memory of events before, during, and immediately after the seizure, and affecting behavior). EEG can show characteristic changes confirming partial (focal) seizures, and may show the focus (the location of the cause). A normal EEG does not rule out seizures. EEG monitoring over several days may be necessary in order to record an event while it is occurring.