SECTION ONE · SOURCES
Sources: Facts 1–40
References and verification notes for the facts in “Your Body Is Doing Its Best.”
FACT 1 · TPF-0001
Your Brain Can’t Feel Its Own Pain
Brain tissue itself does not feel pain. Headaches and other head pain usually arise from pain-sensitive structures surrounding the brain.
Primary source:
National Institute of Neurological Disorders and Stroke
Last reviewed: August 3, 2026
FACT 2 · TPF-0002
One Nostril Is Always on Break
The nasal cycle normally alternates airflow dominance between the two nostrils as tissue on one side becomes more congested while the other side opens.
Primary source:
PLOS ONE / PubMed Central
Last reviewed: August 3, 2026
FACT 3 · TPF-0003
You Are Technically Glowing
The human body produces an extremely faint light through chemical reactions associated with metabolism. This ultraweak photon emission is far below the sensitivity of human vision.
Primary source:
PLOS ONE
The cited study involved five healthy male participants, so the sample was small.
Last reviewed: August 3, 2026
FACT 4 · TPF-0004
Your Pupil Is Just a Hole
The pupil is an opening in the center of the iris. The iris changes the size of this opening to control how much light enters the eye.
Primary source:
National Eye Institute
Last reviewed: August 3, 2026
FACT 5 · TPF-0005
You Can’t Properly Tickle Yourself
When you produce your own touch, your brain predicts the sensation and reduces its intensity. This sensory attenuation makes it extremely difficult to tickle yourself. Introducing a delay can make the touch feel more ticklish because the prediction becomes less accurate.
Primary source:
PubMed
Secondary source:
Last reviewed: August 3, 2026
FACT 6 · TPF-0006
Your Heart Works the Worst Shift
A resting adult heart commonly beats between 60 and 100 times per minute. Depending on the person and the circumstances, that can total roughly 100,000 contractions in twenty-four hours.
Primary source:
American Heart Association
Secondary source:
Last reviewed: August 3, 2026