Sleep occurs in cycles throughout the night, with each sleep cycle taking approximately 90 minutes. Our body’s biological clock controls all of this, and technically the sleep cycle is one of our many “circadian rhythms”. There are 4 identifiable stages in each sleep cycle, and each of them has a significant impact on athletic performance and improvement.
Stage 1 – Lasts for approximately 20 minutes and is the stage where the heart rate slows and the body temperature begins to cool down. The brain activity during this time shows up in “spindles”, which are essentially tightly packed brain wave patterns. These spindles have been linked to muscle memory and internalizing movements learned during the day.
Stages 2 and 3 – Stage 2 is the transition from light to deep sleep, and Stage 3 is complete deep sleep where the body produces very slow waves called Delta Waves. This stage of sleep is often called Slow Wave Sleep (SWS). During this stage HGH is released, blood rushes from the brain to the muscles to initiate recovery and re-energize your body. Additionally, elements of the parasympathetic nervous system are triggered while the sympathetic nervous system is suppressed. All of this supports immune function and normal glucose metabolism during the day.
Stage 4 – Otherwise known as REM sleep, this is the stage where we dream. Our arms and legs are paralyzed, and this is the only stage of sleep where the body doesn’t actually move. This stage of sleep is associated with learning and memory retention, where the hippocampus transfers and filters the day’s information to the neo-cortex, kind of like a computer uploading information and clearing it’s RAM onto a hard drive. During the first few cycles deep sleep periods are longer and REM periods are shorter, but after the 4th cycle the REM periods become much longer and the deep sleep phases much shorter.
Important benefits of Deep Sleep (Slow Wave Sleep):
- Maximum natural production of HGH – this is a hormone that the body naturally produces, and if you want to get stronger and faster then you need your body to maximize natural production. You can only do this by getting adequate amounts of deep sleep. While it is true that most of the HGH released during the night is released in the first few sleep cycles, research has shown that sleep deprivation can throw this off and eliminate the HGH bursts we get in the first few cycles of sleep.
- Suppression of Cortisol production – High levels of cortisol in the night create insulin resistance in the morning, and thus it is linked to coronary artery disease, stroke, type II diabetes, memory loss and cognitive impairment. Additionally, if you are a paleo and/or zone practitioner it will significantly throw off your body’s ability to process glucose throughout the day.
- Suppression of sympathetic nervous system in favor of parasympathetic nervous system – the sympathetic nervous system is what is activated under stress, whereas the parasympathetic nervous system is what the body activates to recover and recuperate.
- Release of Prolactin, which has been shown to have anti-inflammatory properties and therefore may be important for joint recovery.
Important Benefits of REM Sleep and Stage 1 Sleep:
- Spindles are critical to the brains ability to transfer learned muscle movements to permanent memory.
- The period where the Hippocampus transfers information to the neo-cortex, allowing us to recall information, motor skills, and other important information when we wake up and far into the future. Without enough REM sleep we can’t remember and internalize important movements, and therefore athletes in sports that require highly skilled movements (think about all the skill movements in CrossFit, like the Snatch, Clean and Jerk, Muscle-Up) where fractions of an inch are the difference between success and failure, need enough REM sleep to maintain and improve their performance.
- Insufficient REM sleep has a negative impact on the brain as a whole and causes it to function differently, causing it to not function properly. As a consequence, the Hippocampus works less and other parts of the brain, like the Amygdala, work more. Since the Amygdala is associated with rage and aggression, sleep deprived people are often more irritable and moody. Since a positive attitude is so important to a sport like CrossFit, athletes simply can’t afford lapses that will cause them to lose their positive edge
Alright, so now you’ve got some of the basic science behind why sleep matters. Now let’s put them all together and look at the 3 essentials of fitness:
- Think back for a moment to what your life was like before you were introduced to a dedicated exercise regimen. What did you eat? How did you work out? How did you measure your fitness from one week to the next? If you’re like most of us, you probably thought a bit about what you ate and maybe your diet was loosely based on some nutritional tips you’d picked up along the way, but it probably wasn’t based on sound science.
- The same can probably be said for how you worked out – you used the machines that were available, and you probably picked up workout tips from friends, coaches, magazines, etc…Chances are you never did a squat snatch before CrossFit, nor did you stay away from bread and grains in favor of lean meat, nuts, seeds, and veggies. Now consider what your level of fitness and health was then compared to what it is today. Big difference, right?
- CrossFit’s workout methodology is based on science, and like science it is continually evolving. Similarly, Paleo nutrition principles are based on science. Workout methodology and nutrition are two pillars of fitness and general well-being: when you follow scientifically sound principles that are consistently tested, proven, and refined within a large community of experimenters you are going to see strong results. For many of us the results have been quite amazing.