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:
The mice that ate only while active were 40% leaner and had lower cholesterol and blood sugar.
Morgan says blood glucose levels indicate how efficiently your body is processing and storing glucose, and high levels of glucose in the blood after a meal can point out future risks like diabetes. Her experiment found that blood glucose levels after an evening meal were much higher than when the exact same meal was eaten earlier in the day. Morgan says this means we should try to get most of our calories earlier in the day, and have lighter, earlier evening meals when possible.
Professor Jim Horne from Loughborough Universitysaysthat we’re naturally designed to havetwo sleeps a day: a long one at night and another one in the early afternoon. Early afternoon is when our energy naturally dips lower than usual and we have a harder time focusing. In fact, according to an article in The New York Times, lots of cultures around the world break up their sleeping patterns:
The idea that we should sleep in eight-hour chunks is relatively recent. The world’s population sleeps in various and surprising ways. Millions of Chinese workers continue to put their heads on their desks for a nap of an hour or so after lunch, for example, and daytime napping is common from India to Spain.**
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.
Although everyone is different to some degree, we actually all start out as morning people, and continue this way until around age 10. From ages 10–20 we start to sleep and wake up later and later until around 20 years old, when the pattern starts to reverse again and we start waking up earlier. Eventually, around age 55, we are going to sleep and waking up at roughly the same times we did when we were 10 years old.
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 studyof 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. Ina 2007 studyat 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.
The interesting part of this is that the type of work we’re doing makes a difference to which time of the day we should choose to do it in. Here’s how it breaks down:
If you’re a morning lark, say, you’ll want to favor those morning hours when you’re feeling more fresh to get your most demanding, analytic work done. Using your brain to solve problems, answer questions and make decisions is best done when you’re at your peak, according to Scientific American:
Numerous studies have demonstrated that our best performance on challenging, attention-demanding tasks—like studying in the midst of distraction—occurs at our peak time of day. When we operate at our optimal time of day, we filter out the distractions in our world and get down to business.
For night owls, this is obviously a much later period in the day.
On the other hand, if you’re trying to do creative work, you’ll actually have more luck when you’re more tired and your brain isn’t functioning as efficiently. This sounds crazy, but it actually makes sense when you look at the reasoning behind it. It’s one of the reasons why great ideas often happen in the shower after a long day of work.
If you’re tired, your brain is not as good at filtering out distractions and focusing on a particular task. It’s also a lot less efficient at remembering connections between ideas or concepts. These are both good things when it comes to creative work, since this kind of work requires us to make new connections, be open to new ideas and think in new ways.