Circadian Rhythms
Companies are made of humans with the same circadian biology.
Time isn't just a quantity to be filled with work. It's a quality that varies predictably across hours, days, seasons.
Circadian rhythms are internal biological clocks that synchronize organisms to Earth's 24-hour rotation. In mammals, a master clock in the suprachiasmatic nucleus (SCN) - 20,000 neurons in the hypothalamus - orchestrates the body's sense of time. Light resets the clock daily via specialized melanopsin-containing retinal cells. Inside each SCN cell, a molecular pendulum swings: CLOCK and BMAL1 proteins activate Period (PER) and Cryptochrome (CRY) genes, which accumulate and eventually shut down their own production in a negative feedback loop taking approximately 24 hours. Without daily light signals (entrainment), the internal clock free-runs at about 24.2 hours, drifting 12 minutes daily. The SCN controls hormones (cortisol peaks at 8 AM, melatonin at 2 AM), body temperature (lowest 4:30 AM at 96.4°F, highest 7 PM at 99.3°F), and cognitive performance (alertness peaks 10 AM, universal trough at 2 PM).
Business Application of Circadian Rhythms
Companies are made of humans with the same circadian biology. Respecting these rhythms - scheduling deep work during peak windows, meetings during good periods, and admin during troughs - can increase productivity 40% (Microsoft Japan). Violating them (996 culture's 72-hour weeks) causes burnout and reduced innovation despite more hours.