User:Christinagraves/Sandbox

Background and History
"Delta waves" were discovered in the early 1900’s by Dr. Hans Berger, who was the first to record brain activity using electroencephalogram (EEG). Delta waves occur in all mammals, and potentially all animals as well.

Classification and Features
Delta waves, which oscillate between 0-4 Hz occur in the deepest stages of sleep (3 and 4 NREM), also known as slow-wave sleep (SWS). Delta waves begin to appear in stage 3 sleep, but by stage 4 nearly all spectral activity is dominated by delta waves. They are the slowest, but highest amplitude brainwaves. Stage 3 sleep is defined as having less than 50% delta wave activity, while stage 4 sleep was more than 50% delta wave activity. Delta waves, like all brain waves, are detected by electroencephalography (EEG). Delta waves are normally found in healthy individuals during slow wave sleep. Infants and children show more delta wave activity. Delta waves are often associated with another EEG phenomenon, the K-complex. K-Complexes have been shown to immediately preclude delta waves in slow wave sleep.

Development
Delta waves have been shown to decrease across the lifespan, with most of the decline seen in the mid-forties.

Infants spend more time in SWS, and, as such, have more delta waves. Preteens also spend more time in these stages, and have more delta waves.

Neurophysiology
Sex Differences

Females have been shown to have more delta wave activity, and this is true across most mammal species. It has been suggested that this deiscrepancy may be due to larger skull size in males, but this theory has been refuted by intracranial data from female cats, which still show more delta activity.

Brain Localization

Delta waves likely arise in the thalamus.

Cortex Lesions in the suprachiasmatic nuclei have been shown to disrupt delta wave sleep in rats.

Waking someone up during stage three or four sleep, during high delta wave activity may result in confusion.

Disorders
Fever has been shown to increase delta wave activity.

Hypersynchronous Delta Activity

Hypersynchronous Delta Activity (HSD) are continuous, high-voltage (> 150 uV) delta waves seen in sleep EEGs. Sleep deprivation may increase HSD,

Sleep Deprivation

Sleep deprivation has been shown to disrupt delta wave activity.

Sleep Walking and Sleep Talking

Sleep walking and sleep talking most often occur during periods of high-delta wave activity. Sleep walkers have also been shown to have more HSD activity relative to total time spent in stages 2, 3, and 4 sleep relative to healthy controls. Hypersynchronous Delta Activity (HSD) are continuous, high-voltage (> 150 uV) delta waves seen in sleep EEGs. Sleep deprivation may increase HSD,

"Narcolepsy"

Parkinsons

Schizophrenia

Schizophrenics have shown disrupted EEG patterns including delta waves.

"Sleep Paralysis "

"Diabetes and Insulin Resistance" Disruptions in slow wave (delta) sleep have been shown to increase risk for development of Type II diabetes. In addition, hypoglycemia during sleep may also disrupt delta-wave activity.

Biochemistry
Role of Inflamatory Proteins TNF-a Elevated TNF-alpha levels have been shown to disrupt delta-wave activity.

Hormone Secretion and Natural Regulation Growth Hormone

Orexin regulation