Day 5
Light Hygiene BingoDay 5: Light Hygiene Bingo
January 16, 2026
Let's Play a Game!
Most of us are getting the wrong light at the wrong time...
and it's robbing us of our sleep.
Today, try to complete as many of the bingo activities below as you can.
Each time you do, tap the box to turn it orange. Your progress will be saved for next time!
Aim for three in a row, a full column, or go big and try for a blackout (every single square!).
Why are we playing this game today? These habits reinforce the light cues your body relies on to sleep well at night. The more you check off, the stronger your circadian rhythm gets.
Complete the habit, then tap each square to turn it orange ↓
Must-Watch: How Cortisol and Melatonin Control Sleep Tonight
Light Is the Master Signal
Every organ, tissue, and system in our body has its own internal clock — and the “CEO” coordinating them all is a tiny region in the brain called the suprachiasmatic nucleus (SCN). It helps decide when we feel alert, hungry, focused, or ready to wind down.
Light is the master signal that keeps this whole circadian clock on track. Simply put, it tells the body what’s “day” and what’s “night.”
Fun fact: When researchers removed the SCN in rats, they still slept… but in unpredictable naps with no rhythm at all. Total chaos!
Here's the part most people never hear:
Our hormones are governed by light, too. Cortisol (often mislabeled only as a stress hormone but essential for morning energy) and melatonin (our nighttime sleep signal) are both mediated by light:
- Morning light: cortisol rises, melatonin shuts off → we feel energized
- Evening darkness: cortisol drops, melatonin rises → we feel sleepy
In a small study of eight men, switching from dim light to bright light in the early morning (5–8 a.m.) caused an immediate spike of more than 50% in cortisol and rapidly shut down melatonin — i.e. helping the body feel more awake.1
This is why Pillar 1 of this challenge (morning sunlight) is foundational for our sleep.
Waking up at 3-4 AM?
Some research suggests that when cortisol runs higher than expected in the evening or overnight, sleep may become lighter and more fragmented, and awakenings may be more likely.2
(And while that's common, it's not the only reason; things like stress, alcohol, or blood sugar crashes can play a role too.)
The Takeaway
Get your light cues right, and cortisol and melatonin fall back into rhythm, making energy steadier and sleep easier.
Daily Reminders
Morning Sunlight
Get >10 minutes of outdoor light within the first hour of waking.
LUMEBOX Session
- Combined mode
- Behind the neck
- 12 minutes
- Within 2 hrs of sleep
Screen-Free Wind Down
Put away phones and laptops 30 minutes before bed.
Up next:
The Lights-Out Routine
BYO 3-step routine for 2026.
See you tomorrow!
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