Circadian Rhythms Sleep

A circadian rhythm is a roughly-24-hour cycle in the physiological processes of living beings.

Are you sleepy sometimes in the afternoon? Do you seem to handle physical tasks more easily late in the day? If so, you already know about circadian rhythms.

Your body has more than 100 circadian rhythms. Each unique 24-hour cycle influences an aspect of your body's function, including body temperature, hormone levels, heart rate, blood pressure-- even pain threshold. Understanding how these cycles interplay is fascinating. And, in some cases, you may be able to plan your day to take advantage of your body's natural rhythms.

Rhythms control your day

Almost no area of your body is unaffected by circadian rhythms.

Sleep and wake

It may seem you sleep when you're tired and wake when you're rested. But your sleep patterns follow a circadian rhythm.

You're most likely to sleep soundly when your temperature is lowest, in the early hours of the morning. You're also most likely to awaken when your temperature starts to rise around 6 to 8 a.m.

As you age, your brain's "pacemaker" loses cells. This changes your circadian rhythms, especially noticeable in how you sleep. You may nap more, have disrupted sleep and awaken earlier.

Temperature

Your temperature is lowest when you're inactive. And activity can make your temperature rise. But despite these factors, your temperature also follows a definite circadian rhythm.

In the late afternoon, your temperature can be as much as 2 degrees Fahrenheit higher than in the morning. And it will rise and fall even if you never see daylight.