Circadian Rhythm

Overview

The circadian rhythm is the body's internal 24-hour clock that regulates sleep-wake cycles, hormone release, body temperature, and other physiological processes.

Components

• Suprachiasmatic nucleus (SCN) - Master clock in the hypothalamus
• Peripheral clocks - Tissue-specific clocks in organs
• Melatonin - Hormone signaling darkness/sleep time
• Cortisol - Hormone signaling wakefulness

Role in Sleep

• Regulates sleep timing and architecture
• Controls melatonin secretion (evening surge)
• Modulates core body temperature (drops at night)
• Gates sleep propensity throughout the 24-hour cycle

Interaction with Magnesium

Proposed mechanisms: - Magnesium may modulate SCN neuronal activity via NMDA receptors - Magnesium status affects melatonin synthesis - Stress-induced magnesium depletion may disrupt circadian timing

Related Entities

• sleep-quality - Outcome measure
• melatonin - Sleep hormone
• magnesium - Mineral proposed to support circadian function
• hpa-axis - Related stress-timing system

Entity page for circadian rhythm system