For a specific kind of frustration
Training hard.
Sleeping badly. Wondering why.
If your workouts are logged correctly but your recovery isn't matching the effort, this page walks through what the course covers and why sleep is worth examining before you change anything else.
Does this sound familiar?
Your training volume and consistency have gone up, but your lifts, times, or recovery haven't followed the same curve.
You scroll on your phone in bed most nights and assume it doesn't matter much, or you're not sure if it does.
You have coffee in the early afternoon and don't connect it to the trouble falling asleep later that night.
Your wearable gives you a sleep score each morning, but it often contradicts how you actually feel.
The five modules, in detail
What each part of the course actually walks through
Muscle Repair and the Deep Sleep Connection
This module explains the relationship between slow-wave sleep and the release of growth hormone, and how disrupted or shortened deep sleep has been associated with changes in markers linked to muscle repair in published studies. It covers what a typical sleep cycle looks like across a night and why the distribution of deep sleep across those cycles matters, not just total hours.
The Nine PM Light Problem
Controlled studies have measured how short-wavelength light exposure in the evening shifts the timing of melatonin release, sometimes by a substantial margin depending on intensity and duration. This module explains the retinal mechanism behind that shift and what it means practically for anyone using screens in the hours before bed.
Your Three PM Coffee at Eleven PM
Caffeine doesn't leave the body quickly. This module covers the concept of half-life, how it applies to caffeine specifically, and why a substantial portion of an afternoon cup can still be circulating well into the evening for many people, with variation based on genetics and metabolism.
Temperature, Darkness, and Sleep Architecture
A drop in core body temperature is part of the biological process that initiates and maintains sleep. This module reviews research on bedroom temperature and its relationship to sleep quality, along with studies on how even low levels of ambient light during the night can affect sleep continuity.
Why Your Wearable Tells You Less Than You Think
Consumer sleep trackers infer sleep stages from movement and heart rate patterns rather than measuring brain activity directly. This module reviews validation research comparing wearables to polysomnography and discusses why a person's own subjective sense of how they slept often reflects information the device cannot capture.
Who this is not for
What the course does not claim to do
Yalili does not promise faster times, bigger lifts, or specific performance gains. It does not evaluate your personal training program and it does not replace a conversation with a physician if you're dealing with persistent sleep problems, chronic pain, or symptoms that concern you.
What it offers instead is a clear, evidence-based explanation of mechanisms that many people training regularly have never had explained to them in an accessible way. What you do with that understanding is up to you.
Format at a glance
Five modules
Each one focused on a single, specific question.
Written format
Text-based lessons with citations, no video required.
Self-paced
Work through modules on your own schedule, in any order.
Reflection prompts
Optional short exercises to apply concepts to your own routine.