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I’ve mentioned the idea of using circadian rhythms to your advantage a few times (such as in my sleep experiment) but have not gone into much detail about how to leverage them to their fullest. If you pay attention to what your body is doing at different times of the day, you can make significantly better use of your time. In this post we’ll look at the best times to work, nap, exercise and study. So, here are two graphics: here’s the full side-show for the first (sorry but I could not find a much higher resolution version) and the second is a graphic from Wikipedia showing what the body is basically doing at different times of the day:
Okay, so that might be a bit much on the information side. The most important take-away from these graphics is the fact that the greatest alertness happens before noon and the greatest coordination/reaction-time/muscle strength happens after noon. Important note: if you wake up earlier or later, the whole schedule shifts accordingly! Another take-away here is that, after waking, melatonin levels dip quickly, cortisol falls off over time and blood pressure generally rises.
Okay, so this chemical mumbo-jumbo is good and well, but what does it mean to us?
In each day there are at least one or two major tasks I’d like to get done. I don’t know about you, but I like to be alert when I work… so I try to schedule these tasks so that I get them done before noon. As per the napping section (next), I take an afternoon break. When I come back I move on to the other tasks. Simple but effective – I take advantage of the attention peaks and allow myself breaks based upon the circadian rhythm (read on), fitting general tasks in where I can.
I am a proponent of the siesta (aka biphasic sleep, but not polyphasic sleep). There are a number of good reasons to engage in a mid-day nap. Using a mid-day nap you can get not one but two peaks of alertness throughout the day!
I am going to summarize in a moment, but if you really want to understand napping and how to take advantage of these rhythms, I highly recommend you read this well-researched post by brain expert Dr. Wozniak and this follow-up. In it he clearly describes the differences between napping and “polyphasic” sleep, and why each is (or is not) effective. It may be a bit dense, but I guarantee you’ll walk a way with a whole new perspective on your sleep.
Here is a graph from Dr. Wozniak’s post illustrating recorded alertness levels (ability to recall information, etc.) throughout the day (where Time 0 is the moment you wake up):
First, keep in mind that this data comes from actual humans’ ability to recall information – it is not speculative in any way. Dr. Wozniak uses this, as well as his plethora of experience with studying and learning, to conclude the following (drastically trimmed & summarized):
- 3 Hours After Waking: Prime Creativity Time
- 8 Hours After Waking: Prime Napping Time
Notice that we’re talking in terms of time-after-waking. This article+graphic from the Boston Globe does a great job explaining exactly how to nap effectively:
One final thought about napping: a 20-45 minute nap is ideal as quick and restorative “power-nap.” A 45-90 minute falls into the “siesta” category and can help balance a limited (5-6 hr/night) sleep schedule. Anything more than that will be detrimental.
Clearly we can see from the first charts in this post that the best coordination/reaction-time/muscular strength all happen in the mid to late afternoon. If your goal is to perform well, then this seems to be all you need to know.
But if you are exercising simply for the health benefits the debate becomes much more fuzzy. This article at About.com points out that even injuries are fewer in the afternoon, but then concedes that morning exercisers are more consistent. I would stipulate that this is probably related to the fact that attention is greater in the morning.
I’ve spoken with a lot of bodybuilders and personal trainers and they have a few consistent recommendations that I have heard. Some of this may be purely hearsay on their part, but it is worth considering:
- The best time to work out is when you feel the most awake/alert (if you’re looking for the best results from your exercise this makes sense – the more alert you are the harder you push yourself, which means the “better burn” you get – and therefore better results)
- Doing cardio out in the morning on an empty stomach is good for burning calories (the body burns stored body fat for energy because there’s nothing left in the stomach)
In summary, the best time to exercise depends on if your goal is performance or results. If you aren’t too overly concerned with either, it doesn’t seem to matter too much.
We’ve already established that attention is at its highest in the mornings and that it is also a prime creativity time. If actively learning new material is your prime goal, this is the perfect time for it. Odds are, though, that you’re already using this precious attention time for something else. Do not fret!
Recently it has become clear that the time spent sleeping is not a dormant period for the brain. In fact, the brain is actively re-arranging and organizing information during this time – much like de-fragmenting a hard-drive. Recent research has begun to show that sleeping after doing a task improves recall. Researchers has even been shown that the neurons firing during the learning of a new task immediately before sleep also fire during sleep. This study was performed in 2007 on rats running in a maze; it is believed that the rats were “re-running” the maze in their mind during sleep and that the brain naturally reviews what was learned during the day while sleeping.
My interpretation of this is that the morning is best for learning new material while the time preceding sleep is best for reviewing the material. One thing is for certain though: if you’re not getting enough sleep, you’re wasting your study sessions! The brain needs sleep to “digest” the information, and when you are sleep deprived the hippocampus (and other parts responsible for memory formation) are less active.
At different times in my life (and with different experiments!) I have had different priorities. In addition to the 10am natural attention high-point, I am generally a morning person – so I schedule my main goal for the morning after waking up at about 6-7am. Right now I do my main French lessons in the morning (where I learn new words and engage in active conversations; I save the reviewing for the evenings). I have scheduled my workouts for this time in the past when I am training for something or attempting to accomplish some fitness goal.
About noon or 1pm I downshift by making lunch and performing one or two menial tasks (such as creating flashcards, taking care of a few non-stress-inducing emails/calls, etc.) before taking my 2pm nap using my sleep hack to fall sleep in under 2 minutes. I allow myself to sleep without an alarm (I am on a biphasic siesta schedule, but I have never slept past the 90 minute maximum siesta time).
When I wake up again I usually go about the rest of my work for the day and whatever general tasks I need to accomplish. If I did not work out in the morning, I do it a couple hours after waking from the siesta. Around 8pm or so I have a light dinner. I’ll usually relax for an hour or two around this time, either by meeting up with friends briefly or reading a book. Finally, I review (flashcards, etc.) for one hour (two 30-minute sessions) before going to bed at around 11pm-midnight.
Interestingly, you’ll notice my schedule is actually very similar to Mediterranean culture (1 – 1 1/2 hour early afternoon siesta, light dinner late at night, 6 hours or so of nightly sleep, etc). This was not a natural occurrence for me, but the research I have done seems to support the basic lifestyle.
Finally, I should add a caveat to all this: these are suggestions, not rules. The most important rule of all is when you feel most capable to do something. The mind is capable of changing the body in some very significant ways. For example, the very act of getting excited about something can mean that right now is the best time to work on it. Don’t let your desire to be more productive with your circadian rhythms let you procrastinate!