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lack of sleep, cardiovascular performance

Peak performance can be heavily compromised by a lack of sleep

Whether it’s sport or any other type of job, we all know that a lack of sleep and a decreased level of performance are inextricably linked. Therefore, understanding the mechanics of sleep becomes of significant importance to professionals and coaches alike.

The Basics

Just before you fall asleep, beta brain waves (the type of brain waves that occurs when you are awake) are replaced by alpha waves. Alpha waves indicate a state of being awake yet deeply relaxed. Once you have been in this state for between 5-20 minutes, the mind and body will be ready for the first stage of sleep.

Stage One:

This stage can last between 10 seconds and 10 minutes and is a light sleep. Breathing becomes shallow and your muscles rapidly begin to relax (sometimes giving you a sense of falling, which can result in a physical reflex such as kicking out with your legs).

Stage Two:

This stage lasts between 10-20 minutes and experts believe that it marks the beginning of actual sleep, as most people are virtually blind and deaf to most external stimuli.

Stage Three and Stage Four:

You now start to enter the deepest part of your sleep and this is a close as humans get to becoming a hibernating bear or hedgehog! Experts have found that the body’s recovery processes peak during these stages, metabolic activity is at its lowest and the hormonal system increases the release of growth hormone. After about 30-40 minutes at stage four you will retrace stages three and two, but instead of returning to stage one you will move into rapid eye movement (REM) sleep.


A lot happens during REM sleep. Blood flow, pulse, breathing, temperature and blood pressure all rise and your eyes move rapidly as if scanning the environment (fortunately your eyelids remain closed, as it would look a little strange if your eyes were wide open). During this stage dreams often occur, beta brain waves reappear (reflecting an active brain) but the body remains motionless due to the motor cortex blocking neurological activity at the brain stem. This is a very useful mechanism as it prevents us from acting out our dreams.

The cycle of sleep stages is repeated between 4-6 times a night. As the cycles are repeated, the duration of stages three and four decreases while REM increases.

What it means for athletes

So what happens if athletes don’t get enough sleep? Peter Walters identifies three areas that can be affected by a lack of sleep.

Cardiovascular performance

A consistent lack of sleep has been shown to reduce cardiovascular performance by 11%. So how much sleep do you have to miss before this begins to happen? Studies have shown that 30-36 hours of sleep deprivation can result in a loss of performance. If an athlete needs eight hours’ sleep yet only gets six, he/she will accumulate enough sleep debt in 15 days to significantly reduce their cardiovascular performance. Think about an athlete cramming for exams late into the night and getting up for an early morning training session. In just over two weeks his/her athletic performance could be impaired.

Information processing

During sleep our brain has a chance to sort, prioritise and file all the information we have taken in during the day. Mental functioning decreases nearly twice as rapidly as physical performance, so your athlete may feel physically fit but chances are he/she can’t recall the tactical information you gave them yesterday during practice, and they will struggle to make effective decisions during a match or event.

Emotional stability

Even minimal levels of sleep loss result in an increased perception of effort. Your athlete will feel more fatigued, his/her mood will have dropped and clearly they will not be in the type of mental state needed for a top performance.

What can be done?

It is important to establish a consistent sleep pattern. Changing your schedule for more than two days or sleeping more than an hour longer on weekends disrupts your body’s biological clock. If you want to perform when it matters you can’t afford to have you performance hampered by lack of sleep. A good starting point is to remember the four simple rules for a good nights sleep: quiet, dark, cool and comfortable.

lack of sleep, cardiovascular performance