By Simon Hoadley | CrewLAB Research | April 2026
Part 1 of 5: What 18,000 Athletes Taught Us About Sleep
A recent review of scientific literature, reaffirmed what we know: Sleep is Important.
Now we have even more research on the subject.
Key Findings:
- Athletes sleep best on Sunday nights and worst on Wednesday — not after hard training days, but deep in the grind of the regular week.
- Wednesday sits at the bottom of a three-night slide in sleep quality, making it the worst day to schedule a demanding session — and Thursday the day most associated with injury risk.
- Weekend sleep scores are 3.3% higher than mid-week, and the pattern is remarkably consistent across teams, seasons, and age groups.
I built CrewLAB to help coaches see what’s really happening with their athletes — not just the stuff that shows up on an erg screen or a splits chart, but the human stuff. Sleep. Mood. Hydration. The things that quietly determine whether a good training plan actually works or quietly falls apart.
So when we finally had three and a half years of sleep data — over 530,000 check-ins from more than 18,000 athletes — I did what any curious coach would do. I went looking for patterns.
The first thing I found surprised me. Sleep quality doesn’t vary randomly across the week. It follows a remarkably consistent curve — peaking on Sunday night and sliding downhill through Monday, Tuesday, and into Wednesday, where it hits rock bottom. Wednesday is the hump day nobody talks about in training plans. And Thursday? That’s where the accumulated damage shows up. Three consecutive nights of declining sleep, compounding into the kind of fatigue that doesn’t just slow athletes down — it gets them hurt.
The Dataset
Before I walk through the findings, some context on what we’re looking at.
CrewLAB’s wellness check-in asks athletes a simple question each day: How was your sleep last night? Athletes respond on a normalised scale from 0 to 1, where higher is better. It takes about five seconds. There’s no wearable required — this is self-reported, subjective sleep quality, which research consistently shows correlates well with objective sleep measures and is often a better predictor of next-day performance than any device reading.
The dataset covers 533,491 individual sleep responses from 18,163 athletes, logged between September 2022 and April 2026. That’s high school rowers, college crews, masters athletes, and club programs across multiple countries. It’s not a lab study — it’s citizen science at scale, captured through the daily habits of real teams using CrewLAB.
Best and Worst Nights
[Chart 1: Best and Worst Nights]
The pattern is clear and it barely wavers across the dataset. Sunday night is the best night of sleep for athletes, with an average score of 0.716. Saturday comes in second at 0.702. Then it drops — Monday at 0.692, and from there it slides into a mid-week trough where Tuesday (0.688), Thursday (0.687), and Wednesday (0.686) cluster together at the bottom.
The weekend average (Saturday and Sunday) comes in at 0.709. The mid-week average (Tuesday through Thursday) sits at 0.687. That’s a 3.3% gap — small-sounding, but remarkably consistent across teams and seasons. And when you’re talking about the difference between an athlete who slept well enough to adapt to training and one who didn’t, the margins are exactly this thin.
What’s interesting is that the worst nights aren’t the ones most coaches would predict. You might assume athletes sleep worst on Sunday — anxious about the week ahead, or coming off a disrupted weekend schedule. But Sunday is actually the best night. The real damage happens Tuesday through Thursday, deep in the week, when the accumulated pressures of school, work, early alarms, and daily routine stack up.
Why Wednesday Is the Worst Day to Go Hard
Here’s where this gets practical.
If your athletes are sleeping worst on Tuesday and Wednesday nights, then Wednesday and Thursday mornings are when they’re at their most fatigued. Not because of anything you did in training — because of life. The week itself is the stressor.
This means Wednesday is the worst day to schedule your most demanding session. Your athletes are arriving on the back of two nights of declining sleep, carrying a sleep deficit that no amount of caffeine or motivation can fully offset. The recovery from a hard Wednesday session is compromised before it even begins, because Thursday night’s sleep is also poor. You’re loading fatigue on top of fatigue, with no recovery window in sight until Friday night at the earliest.
This doesn’t mean you can’t train on Wednesday. It means you should think carefully about what you programme. Steady state and technical work sit well here — sessions that build volume without demanding peak output. Save your threshold pieces, race-pace intervals, and high-intensity blocks for earlier in the week (Monday or Tuesday, when sleep quality is still relatively higher) or push them to Friday and Saturday, when the recovery runway is longest.
The Thursday Injury Question
I want to be careful here, because we don’t track injuries directly in CrewLAB — yet. But the sleep data strongly suggests that Thursday carries the highest injury risk of any day in the training week.
The logic is straightforward and well-supported by research: injury risk rises when fatigue is high and sleep quality is low. Studies consistently show that athletes sleeping fewer than seven hours per night are significantly more likely to get injured, and that the relationship between sleep deprivation and injury is cumulative — it’s not one bad night that gets you, it’s the compounding effect of several.
By Thursday morning, athletes in our dataset have had three consecutive nights of below-average sleep. If you’ve also scheduled a hard session on Wednesday, you’ve added training stress on top of an already compromised recovery window. Thursday becomes the point where the system is most fragile.
I don’t have the data to prove this definitively. But I’d bet on it. And I’d encourage any coach reading this to look at when their athletes get injured and see if the pattern holds.
What You Can Do About It
If you’re a coach:
Think about your weekly training structure through the lens of sleep, not just physiology. The mid-week trough is real and consistent. Consider front-loading your hardest sessions to Monday or Tuesday, and using Wednesday for lower-intensity, technique-focused, or recovery work. If you run a hard session on Wednesday, at minimum ensure Thursday is light. And if you use CrewLAB’s wellness check-ins, watch for athletes whose Wednesday sleep scores are consistently dropping below the team average — they’re the ones most at risk.
If you’re an athlete:
If you know Tuesday through Thursday is your worst sleep window — and the data says it almost certainly is — that’s where small habits pay the biggest dividends. A consistent bedtime, reducing screen time in the last hour before sleep, and avoiding caffeine after mid-afternoon are simple changes that compound over the week. You can’t control your school or work schedule, but you can protect the margins. The athletes in our dataset who sleep consistently well don’t just perform better — they recover better, feel better, and stay healthier.
What This Makes Visible
This is the kind of insight that used to be invisible to coaches. You’d see an athlete underperform on Thursday and assume they weren’t trying hard enough, or that the training plan needed adjusting. But the problem isn’t the plan. The problem is that the week has a shape — and that shape has a trough right in the middle where your athletes are most vulnerable.
CrewLAB’s wellness tracking makes this visible. You can’t coach what you can’t see. And once you see it, you can’t ignore it.
Sleep has been an ongoing part of CrewLAB research:
CrewLAB has previously written about Athlete Wellness for Coaches.
Catherine Galanti recently wrote about Sleep: The Secret Weapon of Athlete Wellness.
CrewLAB interviewed Matt Barany on Sleep and Stress Management.
This is Part 1 of a five-part series exploring what 18,000 athletes and 530,000 sleep check-ins reveal about recovery, performance, and the habits that separate good teams from great ones. Next up: The Weekend Recovery Effect — why the biggest jump in sleep quality happens between Friday and Saturday, and what it tells us about how athletes actually recover.
Simon Hoadley is the co-founder of CrewLAB and a rowing coach. He believes athletes are more than numbers, that culture trumps training plan every time, and that the antidote to most problems in sport is simple: go outside, with your friends, and exercise.
