Electroencephalogram (EEG) — Relative Power in the Alpha Frequency Band
Measures the proportion of brain electrical activity in the alpha frequency range during an electroencephalogram (EEG).
["This EEG measurement shows how much of the recorded brain activity falls within the alpha frequency range."]
Key facts at a glance
- LOINC
- 60848-9
- Short code
- Alpha freq rel power EEG
- Synonyms
- Alpha freq rel power EEG
- Category
- liver
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 44
- Ref high
- 147
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- eeg
- CPT
- 84075
- SNOMED
- 27550007
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
What is this test?
An electroencephalogram (EEG) records the brain's electrical activity using small sensors placed on the scalp. Relative alpha power expresses the amount of activity in the alpha frequency band as a proportion of the total EEG power analyzed.
Why might I need this test?
This measurement may be included in an EEG to help assess patterns of brain activity. It can provide information when evaluating concerns such as seizures, altered consciousness, sleep-related problems, or other neurological symptoms.
How is the test performed?
A technologist places electrodes on your scalp and records brain activity while you rest, and sometimes while you perform tasks or change sleep state. The EEG recording is analyzed to calculate the relative power of the alpha frequency band.
How do I prepare for the test?
For a routine EEG, wash your hair and avoid hair products or styling sprays on the day of the test. Follow any sleep-deprivation or other preparation instructions provided by your clinician, and do not change medicines unless instructed.
Reference range
Adult: 44-147 U/LN/A
No special preparation required. Avoid fatty meals before the test if possible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Alpha relative power varies naturally with age, alertness, sleep, medication effects, and the part of the brain being analyzed. Higher or lower values may occur with drowsiness, sleep, some seizure disorders, encephalopathy, and other neurological conditions, so this result must be interpreted alongside the full EEG and clinical evaluation.
Short name
EEG alpha relative power
Frequently asked questions
Does this test diagnose a specific condition?
Does higher alpha relative power always mean a problem?
Will I need to sleep during the test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy