Sleep science

Alpha waves and relaxed waking

The first brain rhythm ever recorded in a human, and the one that has to disappear before you can fall asleep.

4 min readbeginnerStrictly reviewed · cited

Roughly 8 to 13 Hz. The rhythm of relaxed wakefulness with the eyes closed.

The one that started it

Alpha is the rhythm Hans Berger recorded in 1929 in the first human EEG. Every band discussed on these pages descends from that recording. The naming convention exists because alpha was found first.

Its defining behaviour is still the easiest EEG demonstration there is: alpha appears when the eyes close and attenuates when they open.

Why it matters for sleep

Sleep onset is marked, in clinical scoring, by alpha dropping away and theta taking over. Falling asleep is in a real sense the disappearance of this rhythm.

That gives it a practical significance: a mind that will not stop working keeps alpha suppressed. The advice about winding down before bed is, in EEG terms, about letting alpha return.

What it is not

Alpha is not a state of enlightenment, and "alpha training" claims run far ahead of the evidence. It is the resting rhythm of a relaxed visual cortex. That is genuinely interesting, and it is also all it is.

Sleep-science pages summarise published research for general education. They are not a substitute for a clinician. If a sleep problem is affecting your health, speak to a doctor, and never change prescribed medication because of something you read here.

Sources and reviewed references

2 references. What these labels mean

  1. 1.Über das Elektrenkephalogramm des MenschenHistorical dream record

    Hans Berger (1929) · Archiv für Psychiatrie und Nervenkrankheiten

    Cited for: The first recording of the human EEG, and the identification of the alpha rhythm: the origin of every frequency band later named.

  2. 2.The AASM Manual for the Scoring of Sleep and Associated Events: Rules, Terminology and Technical SpecificationsSleep medicine

    Conrad Iber and colleagues, for the American Academy of Sleep Medicine (2007) · American Academy of Sleep Medicine

    Cited for: The current clinical standard for how sleep stages are scored, including the EEG frequency criteria that define each stage.