A millisecond can make the difference between winning and losing in sports. Understanding sleep and its impact on performance may help athletes gain that competitive edge.
During sleep, more than 95 per cent of the hormones needed for growth and repair are released.
Sleep-deprived athletes (those who sleep less than a minimum of seven hours per night) are 1.7 times more likely to have an injury than those who sleep more than seven hours.
Sleep helps to consolidate memory, improve judgment, promote learning and concentration, improve reaction time and sharpen problem-solving capacity and accuracy. Sleep is also important for emotional well-being.
Sleep-deprived athletes can begin to show increased levels of depression, stress, anxiety, worry, frustration, irritability, diminished vigour, lower confidence and difficulty in coping with new environmental stressors.
Chronic low-quality sleep or successive nights of disrupted or shortened sleep adversely affects the immune system and increases the risk for infections.
The amount of sleep that a person requires is variable. For elite athletes, however, the general recommendation is nine to ten hours of sleep per day, with 80 to 90 per cent of this being night-time sleep.
Interestingly, if we were to carefully track our high school athletes, we would find that most get less than seven hours of sleep per day.
Is it any surprise therefore that they fall asleep in class, lack focus and have difficulty concentrating? Is it possible that several of their injuries may be linked to sleep deprivation?
University/college athletes also suffer from sleep deficits as they struggle to fit in training, schoolwork and social activities.
Our work with semi-professional basketball players in Bermuda showed more than 60 per cent having greater than normal daytime sleepiness levels and 30 per cent rating their sleep quality as bad.
So how do we know when we should go to sleep and how much sleep is enough?
The human body has a 24-hour internal clock that tells us when we should sleep and when we should be awake.
This sleep/wake cycle is called the Circadian rhythm. For the most part, this cycle is also linked to night and day.
As the place gets dark, Melatonin is released and the presence of this chemical helps to relax the body and allows us to enter a sleep state. Melatonin secretion begins at about 9 pm and stops at approximately 7.30 am. Deepest sleep occurs around 2 pm when Melatonin levels are high.
It is important to note that between 2.30 pm to 5 pm, almost all the systems responsible for optimal sport performance are operating at peak levels. At 2.30 pm, coordination is at its best, followed by reaction time.
Cardiovascular efficiency and muscular strength peak around 5 pm. This period, therefore, would represent the optimal time for physical training activities to be done for most persons.
Sprinters, for example, would probably perform at their best in events held between 2.30 pm and 4.30 pm, since coordination and speed reaction time is highest during this period.
Analytical and tactical sessions involving video analysis may be more effective if conducted around 10 am when there is peak mental alertness.
The Circadian rhythm is not a fixed thing. Night shift workers, for example, would show a reversal in their rhythm over time.
Similarly, athletes who travel to compete in a different time zone will see a shift in their rhythm with time. During the adaptation period, however, performance will be significantly compromised.
Genetics will also impact on the expression of the Circadian rhythm. When people loosely make comments about being a night person or a day person, they are in fact referring to the genetic expression of their Circadian rhythm, which is referred to as the Chronotype.
There are three Chronotypes: Morning type (M-type) also known as the larks; evening type (E-type) also known as the owls and Neither type (N-type) also known as the dove. Most of the population fall into the N-type.
Though not 100 per cent conclusive, research shows that the “larks” have better race times and less fatigue when they compete early in the day.
The “owls” and the “doves” perform better later in the day. Research has also shown that people tend to migrate to sporting activities where training times are in alignment with their chronotypes.
There are simple questionnaires that can be used to determine chronotype and coaches can use these to profile their athletes and to plan sessions at times when they will get optimal output from their athletes.
Though this may be a bit more challenging for team sports, where there will be variation in chronotypes, sleep cycles and Chronotype should not be ruled out.
International elite teams have begun to integrate findings from sleep research into training and it would be advantageous for athletes, coaches and trainers in our region to do the same.
Dr Sharmella Roopchand-Martin is head of the Mona Academy of Sport. She can be reached at sharmella.roopchandmartin@uwimona.edu.jm