Brain waves and their importance for sleep

Alpha, theta, delta – various activities can be observed in our brain during sleep. Depending on the sleep phase, the brain waves also change. You can find out here what significance the different brain frequencies have and which brain waves occur particularly during sleep.

 Table of Contents:

  1. How are brain waves created?
  2. What brain waves are there?
  3. What significance do brain waves have for sleep?
  4. Can brain waves be influenced?
  5. Conclusion

1. How are brain waves created?

The human brain consists of around 80 billion nerve cells, the so-called neurons, which network and communicate with each other using electrical impulses. Each of these pulses produces tiny electromagnetic waves with a frequency of up to 100 oscillations per second (100 hertz). The numerous different waves overlap and form an electromagnetic pattern that can be measured using electroencephalography (EEG). Special electrodes are attached to the scalp to record electrical activity.

Schlafmagazin: Gehirnwellen-Messung im Schlaflabor mit EEG

The different brain waves can be linked to certain states of consciousness and activities. The more intensively the brain actively works, the stronger the impulses and vibrations of the nerve cells are. Which brain waves occur primarily at a certain moment can provide information about brain activity and show what state our brain and consciousness are currently in.

2. What brain waves are there?

As a rule, 5 types of brain waves are distinguished based on their vibration spectrum: gamma, beta, alpha, theta and delta waves.

Schlafmagazin Gehirnwellen Arten Frequenz

Gamma (approx. 40-100 Hz)

Gamma waves are very fast brain waves through which a rapid transfer of information from brain area to brain area can be achieved. They only occur when we are awake and are more pronounced when we carry out demanding tasks and require a high level of concentration and performance. There is still little research into gamma waves, but scientists now suspect that they are also related to the coordination of cell networks in the brain.

Beta (12 – 40 Hz)

Beta waves can be measured when we are in an alert, awake state and are therefore the brain waves that occur primarily during the day in a normal, healthy person. They show a state in which we are fully conscious, receptive and focused.

Low beta frequencies represent a relaxed but attentive position. The middle beta range corresponds to the healthy waking state with normal performance. A high beta wave range, on the other hand, indicates an increased release of stress hormones and can reflect fear, stress or nervousness.

Alpha (8 – 12 Hz)

Alpha waves are slightly slower than beta waves. They usually occur when we go from waking to resting state and form a bridge between conscious and subconscious. Then we are awake, but very passive and relaxed, concentration and receptiveness are reduced and we are in a stand-by state, so to speak, which can also lead to sleep. Alpha waves are associated with a high level of learning and memory, which can actually also be seen when transitioning into or out of sleep. Anyone who goes from the theta range (sleep) to half-sleep (alpha range) when they wake up in the morning is very likely to be able to remember their dreams. If, on the other hand, we switch directly to the beta state, we can no longer remember what we dreamed.

Theta (4 – 8 Hz)

When we slowly transition from wakefulness to sleep, mainly theta waves can be seen in the EEG. They arise in a state in which the conscious mind withdraws and the subconscious mind becomes increasingly active. Theta waves usually occur when falling asleep, in the light sleep phases, dream sleep (REM sleep), but also in deep meditation or hypnotic trance. Special characteristics of this phase are a pronounced imagination, a high degree of plastic imagination and the loss of the conscious thinking function, which is typical for the dream phases of sleep.

Delta (0.5 – 4 Hz)

The slow delta waves occur mainly during deep sleep and hardly occur when awake. During these phases we sleep soundly because consciousness is completely suspended. The body, on the other hand, concentrates on regenerative and healing processes, growth hormones are released and the health of all cells and organs is ensured. For this reason, deep sleep is considered one of the body's most important recovery periods, which we never consciously experience but urgently need.

3. What significance do brain waves have for sleep?

Every night we go through several sleep cycles, which are divided into four sleep phases. In each of these sleep phases something different happens in our brain - the memory is formed, memories are linked together or the energy stores in the body's cells are replenished. Due to these different activities, very specific brain waves appear in the individual sleep phases.

When we sleep, we come to rest and conscious activity shuts down. Therefore, sleep is mainly related to the slower theta and delta brain waves.

Before going to bed, we ideally start to relax and reduce our activity. Beta waves slow down to alpha waves and we enter a calm, perhaps sleepy state. When falling asleep the alpha waves usually change into slow theta waves, consciousness fades and we slip into light sleep. With the change to the deep sleep phase we are then in the delta wave range. In the following REM sleep, brain activity increases slightly again, we dream and primarily theta waves arise.

Brain activity is also very closely related to energy metabolism. Since almost every neuronal impulse requires energy, energy consumption during high activity (gamma, beta) is significantly higher than in phases of reduced activity. During deep sleep (delta waves), energy consumption in the brain is -40% lower than when awake. This is also the reason why our energy stores can be replenished during (deep) sleep and we can literally start the next day full of energy.

 Schlafmagazin Theta- und Delta-Gehirnwellen in verschiedenen Schlafphasen in der NachtAwakening from sleep can lead to the beta waves usual for the waking state via alpha waves, or switch directly from the unconscious theta state to the beta range. However, those who skip half-sleep are less likely to remember their dreams than those for whom the alpha waves serve as a bridge back to consciousness.

Measuring brain waves plays a major role in sleep research because it can provide information about when we are in which phase of sleep. The EEG is therefore an integral part of the so-called polysomnography (PSG), which is considered the gold standard in sleep medicine for the diagnosis of sleep disorders.

4. Can brain waves be influenced?

The human brain is characterized by a high degree of adaptability, also known as plasticity. This allows it to adapt its activity to external influences if these dictate a certain rhythm. This can be particularly helpful in diseases such as Parkinson's or Alzheimer's, which are associated with altered brain activity.

In a certain sense, we can also learn to change our brain waves ourselves by controlling our state of consciousness, for example through meditation or hypnosis. But this doesn't work in all wave ranges. The brain waves can best be influenced in the beta and alpha frequency range, i.e. in the active and passive waking state.

Ways to influence brain waves:

  • Meditation/hypnosis
  • Acoustic signals (e.g. b Binaural rhythms, Sounds with specific frequencies)
  • Visual stimuli (e.g. b Stroboscope light therapies)
  • Neurofeedback
  • Electromagnetic stimulation (e.g. b Transcranial magnetic stimulation)

5. Conclusion

  • Brain waves are created by electrical impulses in the brain and are related to the state of consciousness and activity
  • There are 5 types of waves based on frequency: gamma, beta, alpha, theta and delta
  • During sleep, theta waves (light sleep, REM sleep) and delta waves (deep sleep) occur primarily
  • Brain waves can be partially influenced, for example through meditation, hypnosis, acoustic and visual stimuli or special neurofeedback and stimulation therapies

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