Why can't I sleep even when I'm exhausted?

The inability to fall or stay asleep despite feeling tired is a classic sign of dysregulated cortisol — specifically, cortisol that is too high at night when it should be declining. This pattern is sometimes called "tired but wired" and is one of the most common sleep complaints in functional medicine.

The most common drivers of this pattern include:

• HPA axis dysfunction — the hypothalamic-pituitary-adrenal axis regulates your cortisol rhythm; chronic stress disrupts this rhythm and inverts the normal curve (low in the morning, high at night)
• Blood sugar instability — blood sugar drops during the night trigger cortisol release as a counter-regulatory response, waking you at 2–4 AM
• Chronic inflammation — inflammatory cytokines activate the stress response and suppress melatonin production
• Estrogen and progesterone imbalance — progesterone has a direct calming, sleep-promoting effect; declining levels in perimenopause are a major driver of sleep disruption in women
• Thyroid imbalance — both high and low thyroid function disrupt sleep architecture

Melatonin supplements often do not resolve this pattern because they do not address the cortisol dysregulation underneath. Taking melatonin when cortisol is elevated at night is like trying to sleep with the lights on — the signal is still there.

A functional medicine evaluation measures your cortisol curve across the day using a four-point salivary cortisol test, identifies what is disrupting it, and builds a protocol to restore normal sleep architecture — without relying on sedatives or sleep aids that suppress the problem rather than resolving it.