As time goes by

Time’s passage is “a stubbornly persistent illusion,” Albert Einstein said. Yet in the realm of human health, time is the bottom line; it’s as real as it gets.

Each human being has a limited cache of moments, and when our mortality takes center stage — after diagnosis with a terminal illness, for example — those moments become exceedingly precious.

Time heals many, though unfortunately not all, wounds.

In health care, time is often an adversary. Emergency crews race against it, rushing patients to the hospital before irreparable damage is done. Physicians barrel through their schedules because “time is money”: Primary care visits these days are down to 15 minutes per patient.

There’s more to time than its scarcity, though.

If you stop and think about it, the simple fact that our body keeps time seems miraculous. How is it that our cells divide regularly, with different types cleaving at their own characteristic paces? And what keeps our large-scale loops on track — from our obvious cycles like sleeping and waking to the subtler circuits followed by our immune cells?

By learning more about our bodies’ timekeepers, researchers are discovering how to schedule surgeries and therapies to maximize their effectiveness, and how to reset our internal clocks to improve our health.

As you’ll read in these pages, time is a tyrant, but it’s also a tool — one that we’re only beginning to understand.