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