Enter the Chronotherapists

By OLIVIA JUDSON
NYT

Here’s my prediction for the Next Big Thing in health care: chronotherapy, or therapy by the clock. Yes, in the future, your medicines, your operations, your mealtimes and when you step onto the treadmill or the badminton court — all will be overseen by your personal chronoconsultant.

It’s been known for ages that our bodies have daily, or “circadian,” rhythms. Body temperature is lower in the morning than it is in the afternoon. Blood pressure is low during the night, and rises just before you wake. Muscles are stronger in the afternoon than they are in the morning, and you may have greater dexterity then, too. Badminton players tend to serve more accurately in the afternoon, for example.

But now it’s clear that the body clock is in charge of many other, more subtle processes as well. The content of human breast milk changes during the day. Evening milk is full of compounds that make a baby sleepy; morning milk isn’t. The liver, too, has a strong daily rhythm: many of its activities shut down during the night. Levels of several hormones, including melatonin (involved in sleep) and ghrelin (involved in appetite), rise at night. Testosterone, in contrast, is highest in the morning and lowest in the late afternoon. Cholesterol is made more rapidly at night. Even cancers have a rhythm: breast cancers, for instance, grow faster during the day.

(More here.)