Topic
Sleep
Sleep architecture, recovery, circadian rhythm, and bedtime protocols.
Max KlineHow Many Hours Before Bed Should You Stop Drinking Coffee?
The widely quoted 8.8-hour coffee cutoff comes from a 2023 meta-analysis, but a 2025 polysomnography crossover trial found 100 mg of caffeine four hours before bed did nothing measurable to sleep.
Max KlineDoes Drinking Earlier in the Evening Actually Protect Your Overnight Heart Rate?
A 20,968-person wearable study found each extra drink tracked with about 2.8 bpm higher overnight resting heart rate and 3.8 ms lower HRV, measured against each person's own sober nights.
Max KlineHow Accurate Is Your Smartwatch at Telling Deep Sleep From REM?
Consumer sleep trackers nail asleep-versus-awake but are far shakier at splitting deep, light, and REM sleep, with one validation study finding the Apple Watch off on deep sleep by 43 minutes.
Lauryn BrittDoes Sleep Loss Actually Slow Down How Fast Your Injured Tissue Heals?
Most people treat sleep as the softest variable in recovery — the thing they'll sacrifice first when life gets busy after an injury. The wound-healing literature suggests that's a mistake. In a controlled study of exp…
Max KlineDoes Wearing Earplugs and an Eye Mask in the ICU Actually Prevent Delirium? What the Sleep Data Shows
Here's a finding that hit me sideways because it's so low-tech it feels almost insulting: a randomized trial found that giving hospital patients earplugs, an eye mask, and a scheduled quiet period at night measurably…
Max KlineDoes Breathing Through Your Nose During Sleep Actually Change Your Oxygen and Heart Rate?
Here's a variable most people never isolate: which hole you breathe through at night. Mouth breathing during sleep isn't just a snoring nuisance — it correlates with drier airways, more arousals, and worse subjective…
Max KlineDoes Eating a Big Dinner Late at Night Actually Worsen Your Overnight Heart Rate Variability?
Here's a variable most people ignore when they stare at their morning HRV: what time they stopped eating the night before. I got curious after a string of days where my Oura readiness tanked despite decent sleep durat…
Atlas MercerHow Long Does One Night of Poor Sleep Impair Your Insulin Sensitivity?
The system fails faster than most people assume. In a controlled crossover trial, healthy young men subjected to a single night of total sleep deprivation showed a measurable drop in whole-body insulin sensitivity the…
Atlas MercerDoes Drinking Coffee After a Bad Night of Sleep Restore Your Performance?
The intuition is that caffeine plugs the hole sleep loss creates. The data says it patches one system and leaves another exposed. A 2021 study from Michigan State University's Sleep and Learning Lab (Stepan, Altmann,…
Max KlineDoes Taking Creatine Before Bed Mess With Your Sleep?
Creatine is the most studied supplement in sports nutrition, but the timing question I keep getting is oddly specific: does the dose matter at night? The fear is that creatine is somehow stimulating and will wreck you…
Max KlineDoes Eating Kiwifruit Before Bed Actually Help You Sleep?
I love a sleep intervention that costs almost nothing and has a plausible mechanism, so when the "two kiwis before bed" thing kept resurfacing, I went looking for the actual data instead of the wellness telephone-game…
Max KlineDoes Taking Your Magnesium at Night Actually Improve Your Sleep?
Magnesium is the supplement everyone tells you to take for sleep, and the marketing has gotten ahead of the data in the usual way. So let's isolate the variable. The strongest recent test we have is a 2021 systematic…
Max KlineBlind Your Wearables to Beat the Recovery Nocebo Effect
You wake up feeling rested, pour your morning coffee, and sync your wearable. The screen flashes red: your heart rate variability tanked, your deep sleep was minimal, and your recovery score is a disastrous thirty per…
Atlas MercerThe Superiority of Sleep Regularity Over Duration
The default assumption in human recovery is that sleep volume dictates physiological repair. When a deficit occurs, the standard behavioral response is to extend sleep duration on subsequent days to catch up. This is…
Max KlineWhy Your Dim Nightlight Is Wrecking Tomorrow's Glucose Response
We usually think of light timing purely in terms of melatonin suppression and sleep architecture. But recent data shows a much more direct, mechanical link to autonomic tone and metabolic function. A fascinating study…
