The Cortisol Awakening Response

What it is

The response was characterised across the psychoneuroendocrinology literature rather than in one founding paper, and no founding citation was established in this publication's verification pass, so no originator is claimed here.

The pattern itself is well measured. Cortisol climbs through the late part of the night, before waking, and then rises again more steeply in the first three quarters of an hour after waking. Both halves are circadian. The pre-waking climb is not triggered by the waking, and nothing in the record establishes that it causes either the waking or the thinking that follows.

In effect

There is something here worth knowing, which is why this page is filed as mixed rather than dismissed. Meta-analytic work finds a higher awakening response in people with major depression than in controls, so the measure carries some signal about mood disorder.

The signal does not point where the popular version needs it to. Individual studies split in both directions, and fragmented sleep or waking very early can blunt the response rather than raise it, which is the opposite of what the three in the morning story requires. A pattern that goes both ways in depressed people cannot be the mechanism behind a specific hour of waking.

The defensible statement, if it is worth making at all, is that cortisol is climbing before dawn. Say that, and stop. Do not build a mechanism on it, and do not attach it to a time.

What it does not say

It does not say cortisol wakes you. The rise begins before waking, which rules out the simplest causal reading, and no study establishes any other one.

It does not say a high awakening response means depression or that a low one means health. The association is at the level of group averages in meta-analysis, individual studies disagree, and the measure is not diagnostic of anything in an individual.

It does not carry a verified figure for the size of the rise. The percentage range that circulates was reported rather than verified in this publication's pass and should be treated that way.

This page describes a physiological pattern and the state of the evidence about it. It carries no protocol, no advice and nothing that should be acted on in place of a clinician's judgement.

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