Top 4 Biomarkers to Understand Your Exhaustion

In stressful periods, the nervous system, hormones and metabolism are all under pressure at the same time. That's not an impression, it's biological. The concept of allostatic load explains why you feel depleted, and these 4 biomarkers let you measure it concretely.

1. Cortisol: the thermometer of your stress response

Your quintessential adaptation hormone. With each stressor it rises, mobilises resources, then should come back down. Under chronic stress, it stays elevated around the clock.

Why it matters: When cortisol never fully comes back down, the cortisol receptors in the brain lose sensitivity and the brain keeps pushing for more. The system runs hot: allostatic load climbs, and the energy bill explodes.

Warning signs:

• Non-restorative sleep despite 7 to 8 hours in bed

• High fasting blood sugar

• Intense sugar cravings, especially mid-afternoon

• Night-time waking between 2 and 4 am

• Persistent feeling of being constantly "on edge"

Key takeaway: A 24-hour cortisol profile shows whether your stress axis is overloaded and at what point in the day the pressure is highest.

2. DHEA-S: your biological resilience reserve

An often-overlooked precursor hormone. DHEA-S is used to produce other key hormones like testosterone and oestrogens. When cortisol monopolises resources, DHEA-S drops.

Why it matters: Cortisol and DHEA-S share the same building blocks. Under chronic stress, the body prioritises survival (cortisol) at the expense of vitality (DHEA-S). This is the hormonal depletion mechanism: libido, motivation, recovery capacity and emotional stability all gradually erode.

Warning signs:

• Reduced libido and motivation with no obvious explanation

• Slow recovery after physical effort or a poor night's sleep

• Unusual emotional fragility

• A sense of "ageing faster"

Key takeaway: A low DHEA-S signals that your body has been compensating for too long. It is a sign of depleting reserves, not personal weakness.

3. HbA1c and blood glucose: the readout of your energy rollercoaster

Sometimes, big meals, chocolates and alcohol pile up. Combined with elevated cortisol, these repeated blood sugar spikes become exhausting for the metabolism.

Why it matters: Cortisol stimulates sugar production by the liver. Add fast carbs on top (pastries, chocolates, alcohol on an empty stomach), and you end up with too much sugar in the blood and energy that still crashes. HbA1c reflects this instability over the past 2 to 3 months.

Warning signs:

• Major energy dips after meals

• Brain fog late morning or afternoon

• Needing coffee or sugar just to function

• Night-time waking (blood sugar drop around 2 to 4 am)

• Urgent, hard-to-resist sugar cravings

Key takeaway: Starting meals with vegetables, protein and healthy fats before carbs significantly reduces the blood sugar spike.

4. hsCRP: the signal of silent inflammation

A low-grade inflammation marker, often invisible day to day. Yet it drains your energy continuously.

Why it matters: When cortisol is chronically elevated, it loses its anti-inflammatory effect. Background inflammation quietly rises, impacting the heart, blood vessels and pain perception. It contributes to deep fatigue and the feeling of never truly recovering.

Warning signs:

• Recurring infections (colds, sore throats) through autumn and winter

• Diffuse or joint pain without obvious cause

• Persistent fatigue even after several days of rest

• Low mood, sense of apathy

Key takeaway: hsCRP makes visible an inflammation you may not feel directly, but which depletes your resources continuously.

Cortisol, DHEA-S, blood glucose and hsCRP together map your complete allostatic load. Each illuminates a different angle: stress response, hormonal reserves, metabolic regulation, silent inflammation. The fact that you're "holding on" doesn't mean everything is fine biologically.

At Lucis, we analyse these markers together, in context, to understand how your body is compensating, and provide a personalised plan adapted to your biological profile — not just to reference intervals.

This article is based on our in-depth analysis of chronic fatigue and allostatic load. To go further: Read the full article →

⚠️ The information in this article is provided for educational purposes only and does not constitute medical advice or a medical recommendation. Please consult a healthcare professional before modifying your diet, training, or supplementation.