WHY THIS HAPPENS
Late-evening high-intensity sessions elevate cortisol for 2-4 hours
Sympathetic nervous system dominance from chronic high training load
Under-fuelling — low glycogen and elevated cortisol disrupt sleep
Overtraining spectrum — disrupted sleep is an early overtraining signal
Caffeine too late — half-life of 5-6 hours means 2pm coffee affects midnight sleep
Screen exposure post-ride compounding sympathetic arousal