Sleep Your Way To Better Race Times

  • By Dr. Robert Portman
  • Published February 22, 2013

The average triathlete has a time management problem. Twenty-four hours just isn’t enough time to juggle the competing interests of family, job and training. The problem is exacerbated because we live in a 24/7 world. Since our day cannot be extended beyond 24 hours, adjustments have to be made. For most triathletes, the easiest adjustment is to cut down on their sleep time.

Sleep time has been steadily decreasing since the 1960’s when the average adult slept 8.5 hours per night. Now it is less than seven hours. Most people are aware that sleep deprivation causes a number of behavioral issues, lack of concentration, irritability and increased anxiety. If you are a serious age group athlete you can deal with these issues and hope that your family and coworkers will be understanding.

However, most triathletes may not realize that sleep deprivation can significantly affect the metabolic circuits that determine fitness. When our daily regimen interferes with our genetic programming, it has major implications on training and performance. All of us are familiar with circadian rhythm, especially if we have traveled through multiple times zones in 24 hours. However, our circadian rhythm controls more than just our sleep and eating patterns. It is basically the master time clock that coordinates the release of hormones and other metabolic activators and controls our metabolic pathways.

The master clock is programmed so that we are physically active during daylight hours and sleep at night. This adaptation was crucial because our senses of smell, hearing and sight never developed to the level necessary for us to successfully hunt and be active at night. Although our modern lifestyle challenges our nocturnal limitations, our master clock represents a potent force in determining our daily natural metabolic rhythms.

Our internal clock is the master controller of our fitness level and ultimately our overall health and longevity, so when we interfere with its normal rhythm, it has dramatic effects on the function of our fitness circuits. Research indicates that sleep deprivation impacts endurance performance in three ways: 1) by decreasing the efficiency with which muscle cells convert fuel into energy, 2) by interfering with normal appetite circuits, and 3) by negatively impacting muscle recovery.

Although we live in a 24/7 world, our bodies are still hardwired to operate in the day time. As we move more of our activities into the nighttime, studies show insulin levels increase. In the presence of higher insulin levels, there is a decrease in the efficiency with which carbohydrate is converted into energy and an increase in the conversion of carbohydrate to fat. Any decrease in metabolic efficiency translates into a decrease in
endurance performance.

The second consequence is that sleep deprivation interferes with normal appetite function. Maintaining the caloric balance between exercise activity and food consumption is critical for a serious endurance athlete. Sleep deprivation interferes with the pathways that control hunger and fullness. Sleep deprived individuals demonstrate a significant increase in daily hunger.

The third consequence of sleep deprivation is an increase in cortisol levels. Cortisol is the “anti-recovery” hormone. High levels of cortisol increase muscle damage and reduce the repair and rebuilding of muscle protein. Normally, cortisol levels increase while we are sleeping reaching a peak at about 6:00 A.M. When we are sleep deprived, however, cortisol levels remain elevated. In one study, researchers found an increase in cortisol levels after sleep deprivation that lasted more than two days. Increased levels of cortisol lead to reduced muscle protein synthesis and increased protein degradation, and ultimately poor post-workout recovery.

What does this all mean to the time-challenged athlete? Getting sufficient sleep has to be a critical part of your training regimen. Cutting down on your sleep may give you more time to train, but it will make your training less effective. Research shows that you are better off training a little less yet more effectively by giving yourself the 7.5 hours of sleep you need every night.

Dr. Robert Portman is a well-known exercise scientist and author of Nutrient Timing and The Performance Zone. His latest book is Hardwired for Fitness. To create your own personal nutrition program visit

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