The Four Environmental Signals That Control Your Biology
How Light, Darkness, Temperature, and Movement Regulate Energy, Sleep, and Circadian Rhythm
Kendall Toerner
Published: February 21, 2026
Your body is not random.
It is constantly interpreting the environment.
Every hour.
Every minute.
Most of what you experience — energy, mood, sleep quality, metabolism — is regulated by four core environmental signals.
Not motivation.
Not supplements.
Not biohacks.
Signals.
1. Light: The Master Regulator of Circadian Rhythm
Light exposure is the strongest input your brain receives.
Morning light signals:
- Wake up
- Increase alertness
- Raise cortisol naturally
- Set your circadian rhythm
Bright daytime light supports:
- Stable energy
- Dopamine regulation
- Metabolic timing
Light at night does the opposite.
Artificial light exposure after sunset delays melatonin release, fragments sleep, and shifts your internal clock.
Your body does not respond to the clock on the wall.
It responds to photons.
2. Darkness: The Signal for Repair and Deep Sleep
Darkness is not passive.
It is an active biological signal.
When the brain senses true darkness, it shifts into night mode:
- Melatonin increases
- Nervous system activity slows
- Cellular repair accelerates
- Immune regulation improves
Modern environments rarely provide deep darkness.
Screens, LED lighting, and urban glow weaken the night signal.
Sleep becomes lighter.
Recovery becomes incomplete.
3. Temperature: The Seasonal Signal for Adaptation
Temperature variation tells your body what season it is.
Cool mornings stimulate alertness and metabolic activation.
Natural cold exposure increases sympathetic tone briefly, followed by stronger parasympathetic recovery.
Warmth signals a different metabolic state.
Living in climate-controlled environments year-round removes seasonal input.
Adaptation decreases.
Resilience lowers quietly.
Your body evolved expecting fluctuation.
4. Movement: The Signal of Demand and Capability
Movement is more than exercise.
It is a communication signal.
Frequent natural movement tells your system:
- Energy is required
- Strength is necessary
- Adaptation should increase
Prolonged sitting signals the opposite.
Energy allocation decreases.
Metabolism down-regulates.
Muscle and mitochondrial demand drop.
The body adjusts to what it perceives as required.
What These Signals Actually Do
Together, these four environmental signals regulate:
- Circadian rhythm
- Hormone timing
- Nervous system balance
- Sleep depth
- Metabolic function
- Energy production
When signals are aligned, regulation feels effortless.
When signals are distorted, everything feels heavier.
Why This Matters
Most modern health advice focuses on adding more:
More workouts. More supplements. More optimization.
But if foundational signals are weak or chaotic, results remain unstable.
Change the signals. The system adapts.
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