Sleep and the EEG

Electroencephalography (EEG) is a valuable diagnostic tool for physicians and researchers in the Boston area. One of the areas of science and medicine in which the EEG is extensively used is in the study of sleep and sleep disorders. Sleep is divided into phases, which are identifiable by the patterns observable on EEG recordings. Sleep stages are divided into REM (rapid eye movement) and NREM (non-rapid eye movement) sleep, with NREM further divided into three stages.

NREM Stage 1

Stage 1 NREM sleep, is a phase in between sleep and wakefulness. On an EEG, stage 1 sleep is associated with a transition in the brain from alpha waves (8-13 Hz) to theta waves (4-7 Hz). During this stage, a person’s muscle tone decreases and they lose most of their consciousness of the external environment.

NREM Stage 2

In Stage 2 NREM sleep, conscious awareness of the external environment disappears completely, although a person can be roused from stage 2 sleep fairly easily. In EEG recordings of people in stage 2 sleep, two distinctive patterns can be observed: sleep spindles and k-complexes. Sleep spindles consist of 12-14 Hz waves that last for about half a second. Scientists in Boston theorize that sleep spindles represent the brain inhibiting certain processes that might otherwise interrupt sleep. K-complexes consist of a brief, high-voltage peak followed by a slower complex. They occur every 1.0-1.7 minutes and are often followed by sleep spindles. They can occur spontaneously, but also occur in response to external stimuli such as sounds.

NREM Stage 3

Stage 3 NREM sleep in Boston is also called “slow-wave sleep” or “deep sleep.” The transition from Stage 2 to Stage 3 is marked by an increase in delta waves, which come to predominate during slow-wave sleep. EEG activity is synchronized, and consists of low-frequency, high-altitude wavelengths. Dreaming sometimes occurs in Stage 3 NREM sleep, although it is less common than in REM sleep. Slow-wave sleep is believed to be associated with consolidating memories within the brain.

REM Sleep

REM (rapid eye motion) sleep is characterized by rapid, random movement of the eyes. It generally comprises 20% to 25% of total sleep in adults, occurring in four or five periods during the night. Infants spend as much as 80% of their sleep time in REM. It is during REM sleep that dreams are most likely to occur. On an EEG, REM sleep can be seen to involve higher-frequency, lower-amplitude neural oscillations than NREM stages of sleep. REM EEG patterns are also more random and variable than EEG patterns during NREM sleep. Currently, evidence suggests that REM sleep may be important for consolidating procedural and spatial memory, whereas slow-wave sleep is more strongly associated with consolidating declarative memory. REM sleep is also thought to play a significant role in neural development, especially in infants.

EEG FOR INSOMNIA IN BOSTON 

EEG Neurofeedback in Norfolk County, Boston

A Brief Guide to EEG Brainwave Frequencies

Neurofeedback therapy, available in Mansfield and Norfolk County, is a cutting-edge new approach to managing the symptoms of a wide variety of disorders, including attention deficit hyperactivity disorder (ADHD), anxiety disorder, migraine headaches, and other psychological and pain disorders. Neurofeedback therapy uses electroencephalography (EEG), in which electrodes are attached to the scalp to measure the frequencies of electrical oscillations generated by collections of cells in different regions of the brain. Research has indicated that many conditions, including ADHD and anxiety, are associated with abnormal brainwave frequencies in certain areas of the brain that differ from those of “normal” individuals. Neurofeedback uses sound and images, often in a video game like setup, to teach individuals to consciously alter these frequencies to improve psychological or pain symptoms. There are several types of brainwave frequencies, which are associated with different states of consciousness and types of mental activity. These neural oscillations are referred to as “brainwaves” because, when displayed as an EEG reading or expressed using mathematical equations, they take the form of a wave. There are alpha, beta, theta, gamma, and delta frequencies. This article is a brief beginner’s guide to what these frequencies mean.

Alpha Brainwaves

Alpha waves are defined as neural oscillations that fall within the frequency range of 7.5-12.5 Hz. Alpha waves are notably generated in the occipital lobes, the region of the cortex at the back of the brain associated with visual processing, when a person is awake with their eyes closed. Alpha frequencies are associated with relaxation. Early work with EEG neurofeedback was focused on training people to enter the “alpha state” more easily. Alpha biofeedback has potential applications for treating depression, as well as seizures. Some types of zen meditation are associated with increased alpha waves. They are associated with a mentally restful state, as opposed to active mental attention.

Beta Brainwaves

Beta brainwaves have frequencies ranging from 12.5 to 30 Hz. Beta states, unlike alpha states, are associated with normal waking consciousness and active mental attention. Neurofeedback therapy for ADHD involves using EEG feedback to change from alpha to beta frequencies in certain areas of the brain, including the prefrontal cortex, to increase attention and reduce impulsiveness.

Delta Brainwaves

Delta brainwaves are high-amplitude, low-frequency brainwaves that fall in the range of 0-4 Hz. Delta waves are most strongly associated with deep non-REM stages of sleep, which is known as “slow-wave sleep.” EEG studies of infants and young children have shown that infants spend a lot of time in slow-wave sleep, and that even during wakefulness, children from infancy to as old as five years produce delta waves. Disruptions of delta states are implicated in a number of disorders. For example, in fibromyalgia, research using EEG neuroimaging has revealed the presence of alpha wave intrusion during sleep, when alpha waves appear when actually delta waves should be predominant. This involvement of brainwave frequency in sleep in people with fibromyalgia has led researchers to explore the potential of neurofeedback therapy for treating this difficult and pervasive disorder. Another disorder involving delta-wave dysregulation is schizophrenia. Reduced delta wave activity during sleep, along with increased delta activity during wakefulness, have been shown to correlate with negative symptoms of the disorder such as amotivation, poverty of speech, and the inability to experience pleasure. Disrupted delta wave activity is found in a wide range of other disorders, including depression, anxiety, obsessive-compulsive disorder, and narcolepsy.

Theta Rhythms

Theta brainwave rhythms have frequencies of 4-7 Hz, and are detectable with EEG sensors when emitted in the cortex. Cortical theta is most common in young children. In adults, it often appears in drowsy or deeply meditative states, though not in the deepest stages of sleep. It is associated with REM sleep (rapid eye movement), which is when most dreams occur.

Gamma Brainwaves

Gamma frequencies range in frequency from 25-100 Hz. Research into gamma waves has provided evidence that these frequencies may be heavily involved in what we experience as subjective consciousness. These frequencies have been observed in association with the coordination and synchronization of different brain areas involved in conscious awareness, notably visual awareness. Interestingly, EEG neuroimaging research involving monks in meditative states have demonstrated a correlation between gamma activity and transcendental states of consciousness. In a 2004 study, when Tibetan monks were instructed to generate a sense of compassion, they correspondingly generated rhythmic, coherent activity in the 25-40 Hz range. Gamma synchrony may be involved in the bliss, compassion, and tranquility associated with transcendental meditative states. Neurofeedback training may one day be used to help train novice meditators to achieve these states of consciousness, although scientists are still exploring the role of gamma waves in consciousness.

Neurofeedback therapy in Mansfield works by using EEG measurements of brainwave frequencies to help train people to learn to alter their brainwave frequencies at will. Many psychological and pain disorders, including ADHD, anxiety, and fibromyalgia, have been shown to involve underlying brainwave dysregulation. Using neurofeedback therapy, you can actually learn to change these frequencies at will. For example, a child in Mansfield with ADHD may have excessive alpha activity in some brain areas, and can be trained to change to beta frequencies associated with mental focus and concentration. Neurofeedback therapy in Mansfield is an excellent therapy option, and lacks many of the side effects associated with various medications.

EEG NEUROFEEDBACK - HOW IT WORKS