Circadian Rhythm

The Ultimate Sleep Biomarker To transform your rest, you must focus on one critical metric: your resting heart rate. Lowering this number before your head hits the pillow serves as the ultimate signal that your body is ready for repair. High-value rest isn't just about the time spent unconscious; it's about the physiological transition into a parasympathetic state. Aside from physical intimacy, any activity that spikes your heart rate late in the evening acts as a barrier to the deep, restorative phases of sleep your brain requires to function. Intentional Fasting and Light Hygiene Digestive labor is a silent sleep killer. Consuming food too close to bedtime forces your body to divert energy toward digestion rather than cellular cleanup. Aim for at least a four-hour gap between your final meal and sleep to allow your heart rate to drop significantly. Complement this by strictly managing light exposure. White and blue lights from modern devices aggressively suppress melatonin release. Switching to amber or red tones in your home creates a biological runway, telling your circadian rhythm that the sun has set. Reconciling Your Internal Dialogue We often struggle to sleep because our "internal board of directors" refuses to stop meeting. Bryan Johnson suggests a proactive wind-down where you acknowledge the different versions of yourself—the ambitious one with new ideas or the anxious one reviewing mistakes. If you don't address these voices during a dedicated 60-minute wind-down, they will wait until you are vulnerable at 2:00 a.m. to demand your attention. Writing down ideas for the next day effectively "clocks out" these personas, granting you the psychological permission to rest. The Myth of Making Up Sleep Your body operates on a strict schedule, not a flexible bank account. Bryan Johnson compares missing your bedtime to a missed garbage truck; the glymphatic system clears waste from your brain at specific intervals. If you aren't asleep when the "truck" rolls through, the metabolic trash accumulates. Consistency outweighs duration because regularity locks in these biological cleaning cycles. While it is vital to avoid becoming a "fragile optimizer" where a single light switch causes a panic attack, the principle remains: your body thrives on the predictability of routine.