I keep seeing the same claim go around: evening workouts wreck your sleep.
I can actually check that. So I went through 233,917 workouts and 27,609 nights of sleep from 745 athletes on athletedata.health, scored each night against that person’s own normal, and looked at what their sleep did after easy versus hard sessions.
The hour of the workout barely mattered. How hard they went mattered a lot.
After a hard session, HRV came in lower and resting heart rate higher than that athlete’s usual night. After an easy session, both looked better. That held whether the workout finished at lunchtime or late evening, because it follows the strain you put in, not the time on the clock.
The one place timing did bite: hard sessions that finished within about two hours of bed. Those were the worst nights in the whole dataset. REM and deep sleep dropped, and so did HRV. Give the same session three or four hours of room before bed and most of that went away.
Easy sessions were fine at any hour. An easy spin an hour before bed still came out a touch better than average.
None of this argues with the research. The big four-million-night study everyone screenshots (Leota 2025) found the same shape: a timing-by-intensity effect with roughly a four-hour line, not a blanket “no evening exercise” rule. The popular version just flattened it into something punchier and wrong.
So if you train late and sleep fine, you are not doing anything wrong. Keep the easy work wherever it fits your day. Move the hard intervals and the heavy lifting a few hours earlier when you can.