High phase
The high phase is the first half of every biorhythm cycle, the stretch where the curve sits above the centre line. The classic method links it to the days when that area responds best: energy for the physical cycle, balance for the emotional, clarity for the intellectual. It lasts half the cycle, then the low phase takes over.
The name comes from the chart: each cycle is a sine curve that starts at zero on the day of birth, rises, peaks a quarter of the way through the cycle and returns to zero at the halfway point. Everything above the line is the high phase.
Not every day of the high phase counts the same: near the peak the method places the best days, near the edges the days of transition. That is why the chart says more than the label alone.
For someone born on 15 June 1990, on 2 September 2026 both the physical cycle, on day 4 of 23, and the emotional one, on day 13 of 28, are in the high phase.