What is the reference range for Cortisol (before bed)?

The standard reference range for Cortisol (before bed) is Approximately 0.5–4 nmol/L in saliva; method- and time-specific.. Reference ranges vary by laboratory and assay platform — interpret in context of the issuing laboratory's stated range.

Which tests measure Cortisol (before bed)?

Cortisol (before bed) is measured in 1 test on BiomarkersLabs.com, including Advanced Adrenal Stress Test.

Biomarker Reference · Cortisol-HS

What does the Cortisol (before bed) test measure?

Cortisol (before bed) (Cortisol-HS) is a clinical biomarker used in adrenal-stress assessment. The bedtime sample captures the circadian nadir. It is measured in 1 laboratory test on BiomarkersLabs.com.

Reference Range: Approximately 0.5–4 nmol/L in saliva; method- and time-specific.
Units: nmol/L, µg/dL
Measured In: 1 test
Category: Adrenal

Functional medicine optimalFunctional frameworks target levels in the lower portion of the reference range; precise intervals are method-dependent.

What is Cortisol (before bed)?

The bedtime sample captures the circadian nadir. Cortisol should be at its lowest to permit restorative sleep and nocturnal anabolic processes.

Why is Cortisol (before bed) measured?

Elevated bedtime cortisol is strongly associated with insomnia, heightened nocturnal sympathetic tone, and disrupted sleep architecture. In the evaluation of Cushing syndrome, late-night salivary cortisol is a sensitive screening tool. Persistently low bedtime cortisol is less well characterised but may reflect profound HPA-axis downregulation.

Reference ranges

Standard reference: Approximately 0.5–4 nmol/L in saliva; method- and time-specific.
Functional medicine optimal: Functional frameworks target levels in the lower portion of the reference range; precise intervals are method-dependent.
Units: nmol/L, µg/dL

Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.

Tests that measure Cortisol (before bed)

1 test on BiomarkersLabs.com include this biomarker.

BML-ADR-022Comprehensive

Advanced Adrenal Stress Test

Cortisol (before bed) reference range in this test: Approximately 0.5–4 nmol/L in saliva; method- and time-specific.

Related clinical conditions

Related Biomarkers

Frequently measured alongside

Cortisol (awakening)Cortisol-Aw2 tests Cortisol (30 minutes post-waking)CAR+301 test Cortisol (midday)Cortisol-MD4 tests Cortisol (evening)Cortisol-PM5 tests DehydroepiandrosteroneDHEA4 tests Cortisol-to-DHEA Ratio (derived)Cortisol:DHEA3 tests

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