Why are so many Olympic records broken in the afternoon? Does the body perform differently at this time of day than say, early morning? The team at social sharing app Buffer explains how to tap into your body's "clock" to find the optimal times for sleep, exercise, work, and more.


One thing that we’re obsessed with at Buffer is the best times to share on Twitter, Facebook, and LinkedIn. It just so happens that with social networks, the timing of when your posts go out plays a vital role in your success. Since we’ve got our heads in this all day, every day, I wondered if timing plays a big role in other things we do every day. So I looked into how our body responds to timing and how we can utilize that knowledge. It turns out that we actually have a very sophisticated internal body clock that governs almost everything we do, without us even realizing it.

How the Body Clock Works

Our body clock is a small group of cells made up of unique "body clock" genes. These cells turn on and off and tell other parts of the body what time it is and what to do. In fact, most of our individual organs have their own internal body clock cells as well. Let’s take a look at how the internal body clock affects everything we do, and what the best time is for our body to engage in different daily activities. (Note: The BBC did a fantastic video worth watching, explaining more about how our cells work and the secret of our bodyclock.)

Eating: Which Meal at What Time?



A recent study in Cell Metabolism tried to find out, given all things equal, if timing actually makes a difference. Two groups of mice were put onto the exact same diet in terms of caloric intake. The only difference was that the first group had access to the food all day round, whilst the second group only for 8 hours during peak activity. The result according to the researchers was stunning:


So, limiting your food intake to your eight most active hours during the day could be a good idea. We can also dig a bit deeper into the optimal time for eating dinner in particular:

When You Should Eat Dinner






Sleeping: How Long and at What Time?








So, age has a huge bearing on how our body clocks operate and what our optimal sleep times are. You’re probably familiar with how teenagers prefer to sleep in late and go to bed late, but it turns out it’s not just teenage laziness (although it is “just a phase,” since these tendencies lessen as we get older). From age 13-21 we get up later than any other time in our lives. Teenagers are biologically predisposed to sleep and wake later than anyone else. This means they’re often struggling with important cognitive work at school during their least optimal times. A study of school students’ memory function in the UK actually showed that students performed 9% better on the same type of memory tests in the afternoon as they did in the morning.

Another myth, similar to teenagers’ laziness when going to sleep is the fact that we need eight hours of sleep each night. Daniel Krypke famously eliminated that myth recently with a study showing that, we don’t in fact need that amount of sleep to reach our body’s best performance.


When choosing a time of day to exercise, paying attention to your body clock can also improve results, as well as overall happiness through exercising. Physical performance is usually best, and the risk of injury least, from about 3 p.m. to 6 p.m., says Michael Smolensky, an adjunct professor of biomedical engineering at the University of Texas, Austin, and lead author with Lynne Lamberg of “The Body Clock Guide to Better Health.”


Muscle strength tends to peak between 2 p.m. and 6 p.m. Muscle strength in the afternoon is up to 6% higher than at its lowest point in the day, which improves your ability to grip a club or racquet as well as lessening the risk of injury. Another boost for physical strength comes from the lungs, which function 17.6% more efficiently at 5 p.m. than at midday, according to a study of 4,756 patients led by Boris Medarov, an assistant professor of medicine at Albany Medical College in New York.

Hand-eye coordination is best in the late afternoon, making that a good time for racquetball or Frisbee. And joints and muscles are as much as 20% more flexible in the evening, lowering the risk of injury, Dr. Smolensky says. These body rhythms hold true regardless of how much you’ve slept or how recently you’ve eaten. In a 2007 study at the University of South Carolina at Columbia, 25 experienced swimmers did six time trials while sticking to an artificial schedule that controlled for variables like sleep and diet. The swimmers’ performance still varied by time of day, peaking in the evening and hitting bottom at around 5 a.m.

For runners, cyclists, and other endurance athletes, the morning is the worst performance time as well. Professor Greg Atkinson from Liverpool John Moores University says, “Almost every world record in track-and-field athletics and cycling events has been broken in the afternoon or evening.” This could be a result of our body temperature being at its peak later in the day, giving us a natural ‘pre-game warmup’ in a sense. Our receptiveness to pain is also lower in the afternoon, meaning we can push further in endurance sports. For other athletes, however, the morning could be the optimal performance time. Balance, for instance, is higher in the morning, so gymnasts might perform better then.



For those of us who aren’t chasing world records, afternoons certainly seem to be the best time for exercise. This can even help us sleep better:














How Light Affects Our Body Clocks

Light is the single biggest external factor that affects our internal body clocks. Each of us has a slightly different internal time, which can range from a 22 hour cycle (a fast body clock, associated with morning larks) to a 25 hour cycle (a slow body clock, which night owls would have). The average is around 24.5 hours.





  • Our body clock becomes less active






Some Other Cool Facts


The Best Time to Drink

If you drink the same amount of alcohol at different points in the day, you will have the same blood-alcohol level, but it wil affect your brain differently. In the late afternoon/early evening our body clock is at its peak, so alcohol will have a lower effect on our cognitive ability. Lucky for us, this is right about the time for post-work drinks, so we can enjoy alcohol without it knocking us about like it would in the morning, or making us sleepy like it would at lunch.

The Best time for Medication

Adjusting the time of medication in a recent study damaged 5x fewer healthy cells and was 2x as effective at killing cancerous cells. Administering medications like chemotherapy which can kill healthy as well as diseased cells can be hugely affected by our body clocks. This study showed that if fewer of our healthy cells are active when the medication is administered, it will hurt less of them and be able to target the diseased cells better.

The Best Time to Have a Baby

More babies are born between 3-5 a.m. than any other time. Actually, this distinction is becoming less obvious as more and more births are affected by medical intervention, but the extremely relaxed state of our brains and muscles at this time and our lowered pain sensations mean not only is this a popular time for natural births to occur, but probably the best time you could choose as well.



Why most Olympic records are broken in the afternoon: Your body's best time for everything | Buffer


Image via Aaron Amat (Shutterstock).


Want to see your work on Lifehacker? Email Tessa.