During winter, I kickstart my mornings with 20 minutes under a full-spectrum light therapy lamp while sipping warm lemon water--this mimics sunrise and boosts cortisol naturally. I've found keeping a consistent 6:30 AM wake-up time critical, even on weekends, paired with a strict 1 PM caffeine cut-off to protect sleep quality. When I implemented this during our frosty New Zealand winters, my Garmin sleep scores jumped from 72 to 88, and my kettlebell swing endurance increased by 37% in just three weeks.
In winter, I adjust my circadian routine by being much more intentional about light, timing, and stimulants because I cannot rely on daylight to do the work for me. The goal for me is to protect training quality, not just sleep duration. The most important rule I follow is a fixed wake time, even on rest days. I wake up at the same time year round and expose myself to bright light within the first 20 minutes. When natural light is limited, I use a high lux light source while I hydrate and move lightly. This anchors my circadian rhythm and makes early training sessions feel far less sluggish. If I train later in the day, I still keep that morning light exposure non negotiable. I also shift caffeine earlier in winter. My cutoff is eight hours before bedtime, sometimes earlier if training intensity is high. Cutting late afternoon caffeine was uncomfortable at first, but it improved sleep depth and next day readiness more than any supplement ever did. In the evening, I dim lights aggressively and avoid overhead lighting. This contrast between bright mornings and dark evenings matters more in winter than summer. The improvement showed up clearly in my metrics. My resting heart rate stabilized, heart rate variability improved, and perceived exertion during key sessions dropped. Subjectively, my warm ups shortened and my mood during training was more consistent. For me, winter performance is about replacing missing sunlight with structure. When light, wake time, and caffeine are controlled, training quality holds even when days are short.