Fighting your Circadian Rhythm: Dealing with the effects of disrupted sleep cycles on willpower, and the knock-on effects to your physical training and diet

By Trent Gardner, MTI Contributor


In 2015, I started working a position that required 24/7 coverage. To ensure a fair distribution of the downsides of late-night work, my organization implemented a rotating shift pattern, requiring an 8 hours shift in sleep schedule every six weeks. Unsurprisingly, this continuous cycling led to a chronic disruption of my Circadian rhythm. I would struggle to fall asleep at any time, tossing and turning until it was time to get up. I would struggle through the day, buoyed by caffeine. This would repeat night after night until I was so tired that I could fall asleep anywhere. The consequences of this on my mental and physical health were obvious. I continued to train, and set lofty goals to meet. But I struggled physically with slow recovery, and high injury rates. More importantly, I struggled to consistently execute the training and diet regimes that were needed to meet my goals. The mental fatigue created by sleep disruption left me short of the willpower to execute an intense training regime, and short of the energy to cook healthy food for myself that I would actually eat. Learning how to structure my training around these challenging facts was key to maintaining physical fitness while avoiding burnout.


Sleep Disruptions for Tactical Athletes

Most tactical and law enforcement positions feature a less severe version of this shift work. The individual is subject to constantly varying wake-up times, usually with significant and highly active nighttime operations. Additionally, maintaining physical fitness is a demand rarely met with resources, forcing the member to scrounge for time (and energy) to maintain their readiness. All of these factors contribute to Circadian rhythm disruption and chronic fatigue, enhance decision fatigue, and reduce the ability to train.


Circadian Rhythm Disruption, Physical Exhaustion, and “Decision Fatigue”

What is Circadian Rhythm disruption? It is the alteration of your natural sleep cycle as your body works to cope with the long-term demands of your work. Importantly, it is the shifting of your body’s natural sleeping clock into a time and regime unsuitable for the demands of your work. If your Circadian rhythm keeps you up till 0200, and you have a showtime of 0430, you will constantly fight your body’s natural instincts. Consequently, you fail to get enough sleep, and even the time you spend asleep is poor quality. This swiftly contributes to a high level of chronic and mental fatigue. On the most obvious level, this contributes to a persistent decline in physical performance. It’s not uncommon for individuals in this situation to see significant declines in physical strength and aerobic capability, paired with increased injury risk. But more insidiously, it saps your mental energy, with significantly greater consequences [1] [2]. This decrease in mental energy increases your susceptibility to “decision fatigue”, where the act of making decisions causes a subsequent decrease in decision making ability [3].

The Strength Model of Self Control suggests humans have a finite ability to self-regulate. A way to frame this is the concept of a mental battery containing all of our self-regulation for a given time frame. Once our battery is expended, we continue to operate, but we no longer take deliberate actions. We rely on our subconscious, following the easiest path, hunting for high calorie food, and reacting on emotion, not reason. Importantly, fatigue pre-drains our battery. It reduces the amount of self-regulation possible before we even wake up [3].

What kind of actions drain this self-regulation battery? Really, anything that requires the usage of conscious decision making. Some examples:

  • Decision making at work
  • Deciding what to eat for dinner
  • Deciding what to wear
  • A long run based on HR zones that requires continuous monitoring of HR.

Conversely, many actions fall into semi-conscious decision-making. A very obvious place this happens is when we fall into a “flow state”, where we automatically respond to stimuli without conscious thoughts. Examples of semi-conscious activities:

  • A long slow run for time
  • Executing a well-drilled event at work.


What Can We Do About It

Reducing Complexity

To meet this challenge, we need to reduce as many of our complex decision points to pre-planned reactions. We look ahead, and pre-plan our responses to certain stimuli or triggers. This allows us to remove those stimuli from the conscious decision-making realm, and rely on our plan and on our pre-drilled muscle memory. By identifying and consolidating decision points in our everyday lives, we can improve our performance and leave ourselves decision-making capability for unexpected events. 

It is key to remember, this should not become another high complexity process. We don’t want to beat an already dead horse. The central tenet of this is clearly defining our objective. We have to know what hill we are trying to climb. Am I trying to prepare for a selection, or an Ironman? Do I need to maintain a certain level of body composition that drives nutritional choices? Or am I just trying to get big for my ego. Once we have narrowed down our objective, we can define our necessary intermediate actions, and plan to achieve them.

Diet and Other Flexible Areas

Some aspects of decision making are easy to preplan. For example:

  • Buy five sets of an outfit to wear every day to work.
  • Plan your meals for the week on Sunday.
  • Meal prep your meals for the week on Sunday.

These are easy areas where cutting down on decision making is well-documented.

Physical Training

Physical training is where it gets tricky. To achieve your goals, you sometimes need to perform multiple sessions a day, or execute complex workout regimes based on your HR. However, the first task is to assess if your workouts are truly supporting your goals. Remember, we are energy and recovery limited here. Clear definition of our primary objective is crucial. It is easy to get caught up in the “ego” trap, and continue performing work that doesn’t continue directly to our goals because it makes us look good. Equally dangerous is the “feel good” trap. These are workouts that we just like doing, likely because we’re already good at them. 

To break out of these traps, review all your workouts with your primary objective in mind. 

  1. Define the bare minimum to achieve primary objective e.g. If I want to squat 400 lbs, I need to squat in my workouts.
  2. Define secondary elements that contribute to your primary objective. For example, core work to improve core strength for squats.
  3. Define the tertiary elements that contribute to other objectives e.g. Curls for the girls.
  4. Get rid of complicated warm-ups. If you can’t comfortably squat after ten minutes, you need sleep or surgery, not a workout.
  5. Start your workout with the bare minimum. Follow up with the secondary elements. Do the tertiary elements only if it’s a good day. If you feel unengaged after your minimum, GO HOME. 

Thirty minutes of primary work every day will get you farther than an hour of bullshit every other day. By defining and committing to our primary needs, we can confidently go home when we’re tired, without pressing through into overwork. The end goal is a steady state of working out, where we consistently achieve our primary goals, and occasionally get in movements that feed our secondary objectives.



Committing to planning is essential in combating fatigue. Attempting to perform at the same level when we are in deep Circadian disruption is bound for failure, but we can still achieve our goals. The most important thing is prioritizing which goal is the most important, and making a deliberate plan to achieve it. We must deliberately reduce distractions, and move as much decision making as possible to times when fatigue is lowest. By reducing the need to expend mental energy on non-necessities, we can save our willpower for when we most need it.

Born and raised in California, Trent G. grew up surround by the mountains of the Sierra Nevadas. This environment developed an enduring passion for the mountain environment. After college, he joined the Air Force as commissioned officer. During his seven years on Active Duty he flew and instructed in the MQ-1 Predator and MQ-9 Reaper. After separating from Active Duty, he moved to Denver to work as a Software Engineer specializing in Software Assurance for DoD programs.

A competitive wrestler for many years, he took up skiing and trail running during his time in the military. He has summited the highest points in five southwestern states, including Mt. Whitney. He is a long-time MTI subscriber, and use’s Rob’s programming to further his goal of summiting Mt. Denali (and maybe skiing down). 


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