Calculate your optimal wake-up times and bedtimes using 90-minute sleep cycles (NREM + REM) and age recommended ranges.
In FY 2026-27, science suggests that humans sleep in 90-minute cycles. Waking up at the completion of a cycle (e.g., 6h, 7.5h, or 9h) prevents 'sleep inertia' and ensures you wake up alert rather than groggy.