Your circadian rhythm — that internal human clock that directs the 24-hour sleep-wake cycle — influences a lot more than when you go to bed and wake up.
We knew that the circadian cycle impacts our physiology, but researchers are just beginning to understand how the human clock impacts our brain function.
Some studies have demonstrated that individual differences in the time of day when we are most alert, called the circadian arousal, correlate with performance on a variety of cognitive tasks.
Our performance peaks at specific intervals of the day, according to researchers at Brigham and Women's Hospital and published in Journal of Investigative Medicine.
For morning types, sometimes called doves, performance generally peaks in early morning hours, while evening types, sometimes called night owls, perform better in the afternoon or later in the day.
As a general rule, older adults, age 50 and up, tend to be doves, while younger adults show an opposite pattern.
When tested at various points throughout the day, both young and older adults show dramatic differences in memory performance. Younger people tend to improve as the day progresses, while older people generally exhibit a decline, according to the study.
Tapping into your brain’s peak performance is similar to tuning in to the ebb and flow of the ocean’s waves. As Adam Sinicki writes, “it’s important to familiarize yourself with the natural, organic flow of your creative abilities and step-back every now-and-then to rejuvenate.”
7 a.m. to 9 a.m.
"The perfect moment for bonding with your spouse is right when you wake up," Ilia Karatsoreos, PhD, a neuroscientist at Rockefeller University, told Prevention.com.
The reason? Levels of oxytocin — the so-called love hormone— are sky-high upon waking, making it the best time for intimacy of all kinds.
Your husband's circadian rhythm is nearly the same. British researchers found naturally high morning oxytocin levels in men gradually decreased as the day wore on.
9 a.m to 11 a.m.
Tap into your creativity while your brain has moderate levels of the stress hormone cortisol, says Sung Lee, MD, secretary of the International Brain Education Association.
Because you're primed for learning, take on tasks that require analysis and concentration.
Reasonable amounts of cortisol can actually help your mind focus and it’s present at any age, according to MSN Health. A University of Michigan study found that college students and retired adults were both mentally quick in the morning.
11 a.m. to 2 p.m.
Now is the time to tear through your to-do list and do your heavy lifting. The sleep hormone melatonin has dipped sharply from its late-evening and early-morning peaks.
So now you’re ready to tackle those projects you’ve been putting off, according to German researchers. They found that reaction time and the ability to accomplish several tasks were strong in the middle of the day.
René Marois, PhD, director of the Human Information Processing Laboratory at Vanderbilt University, says checking items off one at a time can help you stay focused.
When you attempt to juggle tasks simultaneously it puts additional demands on your brain, making you more likely to lose concentration and make slip-ups.
2 p.m. to 3 p.m.
Take a break. If you commonly feel sleepy about now, it’s possible your body's circadian rhythm is in a short waning phase, commonly referred to as a mid-day slump, according to a Harvard study.
Now is a great time to schedule lunch, comb through light reading, or take a brief nap.
Keep in mind, as your lunch is digested, that your body is drawing blood away from your brain to your stomach. If you are at work, a brisk walk or drinking some water will be helpful to get blood moving away from your stomach and back to your head.
3 p.m. to 6 p.m.
"Although your brain is not as sharp as earlier, you're more easygoing, so plan a low-pressure meeting for now. If you've already left work, pick an activity that is as different from your job as possible," suggests Paul Nussbaum, PhD, a clinical neuropsychologist and author of Your Brain Health Lifestyle.
“Exercise is a perfect one: Studies show that grip strength, manual dexterity, and other physical skills are at their strongest by evening, but if you work out too late, the residual adrenaline may interfere with sleep for some people,” reports Prevention.com.
6 p.m. to 8 p.m.
Researchers found that the brain enters something called wake maintenance, when its production of the hormone melatonin is at its lowest. As a result, you are likely to catch your second wind, so it’s a good time to tackle some personal tasks, such as shopping or walking the dog or engaging in family time.
Studies also show that your taste buds are highly active now because of circadian variations in hormone levels, reports Prevention.com.
8 p.m. to 10 p.m.
“There's an abrupt transition from being wide awake to feeling sleepy as melatonin levels rise quickly,” report Australian and British researchers.
Meanwhile, levels of serotonin, a neurotransmitter tied to energy levels, start to fade. "Eighty percent of serotonin is stimulated from exposure to daylight, so now you're slowing down," says Rubin Naiman, PhD, sleep specialist and clinical assistant professor of medicine at the University of Arizona's Center for Integrative Medicine.
Now's the time to ease into relaxing, "mindless" activities.
"By nightfall, when your brain is tired, this is a good way to bring yourself down, like walking a lap or two after a big workout," says Naiman.
Relationship of endogenous circadian melatonin and temperature rhythms to self-reported preference for morning or evening activity in young and older people. Duffy JF1, Dijk DJ, Hall EF, Czeisler CA. J Investig Med. 1999 Mar;47(3):141-50.
How to Make Sure You are at Your Peak Creativity and Productivity When You Need to Be. HealthGuidance. Adam Sinicki
Let Your Brain Reign. Prevention, and MSN Health. Sara Reistad-Long. 3 Nov. 2011
Age-related Neural Differences in Affiliation and Isolation. Janelle N. Beadle, Carolyn Yoon, Angela H. Gutchess. Cognitive, Affective & Behavioral Neuroscience. Vol.12:2:269-279
Reviewed April 7, 2015
by Michele Blacksberg RN
Edited by Jody Smith