Biorhythms Aren’t Real, But ‘Peaks’ of Productivity Can Be

You know a theory is janky when even its Wikipedia page has “(pseudoscience)” behind its name in the title. That’s the case with so-called “biorhythms,” or periods of 23, 28, and 33 days that supposedly predict how mentally, physically, and actively on-point you’ll be on any given day. It’s all nonsense, but there are other ways to track your “peaks” in productivity that are more scientifically sound.

What is the difference between a biorhythm and a circadian rhythm?

The idea behind biorhythms is that over the course of those month-long periods, your physical, emotional, and intellectual aptitudes fluctuate rhythmically, up and down, so you should be attuned to your personal schedule and act when each of them is at the top of one of its cycles. Scientists have looked into this and deemed it hogwash, and the enduring belief in this phenomenon has led to some money-grabs wherein influencers or other hucksters try to sell you products that can help you “hack” your own biorhythm to maximise your energy, productivity, and happiness.

Circadian rhythms are a little different, though. Per the National Institute of General Medical Sciences, they’re the physical, mental, and behavioural changes that flow along a day-long cycle and they’re just triggered by light and dark. There’s a whole science behind it (chronobiology), but what it amounts to is this: You get tired when it gets darker, your body sleeps at night, and you should be awake in daylight to get stuff done, ideally feeling alert. You can put a lot of energy into “hacking” your rhythm, but it’s all the obvious stuff: Sleep at night, don’t exercise or look at your phone before bed, go outside in the morning, stick to a schedule, etc.

Biorhythms aren’t real, but circadian rhythms are. You’ll be more productive if you get consistent and good sleep. You don’t need to track peaks and valleys or subscribe to hokey apps to master this.

What is the Yerkes-Dodson law?

Some peaks and valleys are worth tapping into, though. The Yerkes-Dodson law models the relationship between stress levels and performance. It’s been around since 1908, when psychologists Robert Yerkes and John Dillingham Dodson discovered it, and looks like a curve when it’s mapped out, just like “biorhythms” do. It looks like an upside-down U and on the left, you have your low-stress moments, on the right you have your high-stress moments, and in the middle, you have your peak, or the time when you’re just stressed enough to be productive but not totally overwhelmed. The Y-axis shows peak performance at the top and worst performance at the bottom, so you’ll notice that your poor performance times are aligned with having too little and too much stress. Stress is referred to as “arousal” here, too, but we’re just going to stick with “stress.”

When you don’t have enough stress, you’ll be disinterested in your task. When you have too much, you’ll be too anxious to get it done well. The hypothesis Yerkes and Dodson came up with after studying the effects of electric shocks on mice’s ability to perform tasks is that as stress increases, ability also increases because you have motivation.

What does this mean for you? You should study one rhythm, and that’s the way your interest and stress fluctuate. You don’t need to buy an app or self-help book, but pay attention to how interested you are in a given task at any time. When no one is coming over to visit, you may not be interested in cleaning your house. In the hour before a guest arrives, you may be horrified by your environment and try to crash-clean it. The peak time to clean it, then, is a day or two before someone comes over, when you’re motivated and interested, but before you freak out. Apply that to any task you need to accomplish and pay close attention to how you feel in the lead-up to doing it so you can identify your own peak stress and peak productivity times.