The ZZZ Factor

January 29, 2015
Chronically sleep-deprived athletes probably don't realize all the ways they're hindering their performance. By explaining sleep's many physical and mental benefits, you can help them put the issue to rest.
By Art Horne

Art Horne, MEd, ATC, CSCS, is Associate Director of Sports Medicine and Strength and Conditioning Coach for men's basketball at Northeastern University. He can be reached at: a.horne@neu.edu.


In the past decade, recovery has become one of the hottest buzzwords in the athletic performance world. Athletes today go to great lengths to ensure that their post-workout habits help them recover optimally after practices, weightroom sessions, and competitions--whether that means following a special nutrition program, performing a carefully planned cooldown routine, or even using modalities such as hydrotherapy or yoga. With so much time and money spent on recovery aids like these, it's ironic that so many athletes overlook the most easily accessible, affordable, and time-tested recovery booster of all: sleep.

But the value of sleep isn't limited to recovery. Its important role in athletic performance and overall health is well documented, and few things are as intuitive as the need for a good night's rest. Yet how many athletes in your setting truly take advantage of it? If you've ever looked around a team bus and seen heads bobbing up and down as athletes doze off during even short trips, it's obvious that many are sleep deprived.

By educating athletes and coaches, you can help them realize that better sleep habits--or "sleep hygiene," as our team physician Gian Corrado, MD, has called it--can be a secret weapon to improve performance and recovery. The latest research on how sleep affects mental and physical ability suggests that the time athletes spend on the pillow can be just as important as the time they spend in the weightroom and the gym.

SLEEP 101
Let's begin with a short primer on exactly how sleep works. Every human brain has a built-in clock called the suprachiasmatic nucleus (SCN), which regulates our circadian rhythm. The SCN is located in the brain's hypothalamus, just above where the optic nerves cross--and that's important, because light exposure is one factor that can greatly affect circadian rhythms and feelings of sleepiness or alertness.

If you could remove all the external elements of daily life that affect sleep patterns, including stress, schedule demands, alarm clocks, and next-door neighbors' barking dogs, research indicates that most adults would sleep for about eight hours a night (slightly more according to some studies), and teenagers and college-age people would sleep for approximately nine hours. This amount of sleep produces optimal physical and mental health, and in an ideal world, it's the goal everyone should strive for.

What exactly goes on during those hours? Analysis of brain activity during sleep reveals that it can be broken into five unique stages. Stages one and two comprise what is commonly referred to as light sleep, and stages three and four constitute deep sleep. The fifth stage, rapid-eye movement (REM) sleep, is the dreaming stage, and in most cases it occurs only after we have passed through the first four stages. During a typical night of undisturbed sleep, we complete a full cycle through the stages of sleep roughly every 90 minutes.

Each stage has its own function, and stages three and four--deep sleep--are of particular importance to athletes. This is when the natural physical and mental processes of restoration are at their peak, and when growth hormone secretion occurs. Growth hormone is essential for building and rebuilding muscle and other body tissue, so when an athlete doesn't sleep long enough to complete several cycles of deep sleep, they deprive themselves of key physiological benefits.

SLEEP DEBT & PERFORMANCE
Anyone who has pulled an all-nighter while studying for an exam is familiar with the concept of "sleep debt." When the body fails to get an adequate amount of shut-eye, everything from mood to cognitive function to motor skills can suffer. But what about athletic performance in particular?

From a clinical perspective, the actual definition of sleep debt is still up for debate. Several researchers have attempted to set parameters for it and quantify its effects, while others have questioned whether the concept is scientifically valid at all. For this discussion, we'll define sleep debt as what happens when "how much a person should sleep" and "how much they actually do sleep" are different enough that physical and mental effects can be observed.

For athletic performance, both the physical and mental dimensions are important. On the physical side, sleep-deprivation studies have shown that the primary negative effect of sleep debt is a decrease in time to exhaustion during activity. In prolonged performance tests, subjects who have gotten less sleep consistently tire more quickly than those who have gotten more.

Other key physical parameters, such as power output and aerobic and anaerobic performance, are not usually impacted by a mild to moderate lack of sleep. However, ratings of perceived exertion (RPE) are almost always affected when a significant sleep debt is present: Athletes feel they are working harder when sleep deprived, even if performance metrics say otherwise. Some study authors have attributed this to a self-fulfilling prophecy, since tired athletes expect physical activity to be more strenuous and difficult due to their tiredness.

The mental effects of sleep debt, meanwhile, are much more pronounced. And for competitive sports, in which decisions must be made in the blink of an eye and concentration is at a premium, this subject is worth exploring.

Research has shown that reaction time, stress level, alertness, irritability, and overall energy level or vigor are all negatively affected by sleep deprivation. Some studies in this area have looked at extremes, such as three consecutive sleepless nights (which even the busiest student-athlete is unlikely to experience), but others have found that even a relatively mild sleep debt, over time, takes a clear mental toll.

For example, after subjects in one study were limited to four to six hours of sleep per night over a two-week period, their performance in cognitive tests was comparable to that of other subjects who were kept awake for more than 48 hours straight. Another study found that chronically sleep-deprived people were outperformed on a reaction time test by well-rested people--who also happened to be above the legal alcohol intoxication limit for driving at the time.

Findings like these reveal the cumulative nature of sleep debt: If an individual consistently doesn't sleep enough over an extended period, the negative effects are compounded. Four to six hours of sleep a night is common for many high school and college students, so these results are significant.

Sleep debt can also wreak havoc on another key process for athletes: motor learning. It's well known that practicing a given skill leads to improved proficiency, and that the passage of time after practicing further enhances the gains--this is one of the concepts behind "muscle memory." But a recent landmark study suggests it's not the passage of time itself that makes the difference, but rather time spent asleep that causes additional proficiency gains to occur.

In the study, two groups were tested in a specific motor skill, and then retested in the same skill 12 hours later. Members of the first group were initially tested at 10 p.m. and went to sleep shortly afterward. Members of the second group were initially tested at 10 a.m. and did not sleep afterward. When the groups were re-tested, those who had slept showed a statistically significant improvement in performance, while those who had not slept showed no improvement. However, it's interesting to note that after 24 hours, once members of the second group had gotten a night's sleep, their performance at the skill improved significantly as well.

Scientists can't explain precisely why this phenomenon occurs, but something happens within the brain during sleep that causes us to process movements and skills we've learned through practice in a way we can't when we're awake. This fact should be very interesting to anyone who takes foul shots, kicks field goals, executes volleyball serves, or performs countless other athletic activities that rely on precision and learned movement patterns.

Perhaps most interesting of all, several studies have shown that test subjects who suffer cognitive and motor impairment due to a sleep debt are often unaware of their decreased ability. This might help explain why athletes don't take sleep habits as seriously as they should--they don't realize how much it may be hampering their alertness, mental processing speed, reaction time, and other skills essential to athletic success.

BETTER NIGHTS AHEAD
If you could improve athletes' sleep habits simply by summarizing the research in this article and then telling them to hit the hay, I could stop here. But in reality, most sleep-deprived athletes got that way because they don't know exactly what they're doing wrong.

The first priority to address is time devoted to sleep. The aforementioned goal of nine hours per night for teens and college students will seem unrealistic to many, but the closer they can come to that number, the better they'll feel and the more they'll enjoy the health, recovery, and performance benefits of sleep.

Consistency in sleep time is valuable as well. Going to bed and waking up at the same time every day takes maximum advantage of the body's natural circadian rhythm, while having different bedtimes and wake-up times every day can throw off the internal clock. Once a routine is established, athletes will find they are able to fall asleep more quickly and sleep more soundly through the night.

Remember how the suprachiasmatic nucleus is located near the optic nerves? Even small amounts of light can affect levels of melatonin, the major hormone that regulates sleepiness, and that's just one example of why creating the right sleeping environment must be a priority as well. This can be difficult for student-athletes, particularly college students living in dorms, so here are some helpful tips to pass along:

• Eliminate as many light sources as possible when going to bed. This means turning off computer monitors, using dark curtains over dorm windows, and even rolling up a towel and putting it at the base of the door to block light from the hallway. If these steps are not possible, try using a sleeping mask to cover your eyes.

• Try wearing soft foam earplugs to eliminate nighttime noises that might interrupt your sleep. Or, if you're used to some ambient noise at night, use a fan, humidifier, or other appliance that creates "white noise" to make you more comfortable.

• Turn off the ringer on your phone(s) before going to bed. Remember that interrupted sleep can deprive you of the deeper stages of the sleep cycle, which have so many crucial benefits.

• Engage in progressive relaxation activities as you prepare to go to sleep. Being very physically active late at night, exposure to bright light right before bed (for instance from a computer monitor or television), or eating less than two hours before bedtime can delay "sleep latency," making it harder to fall asleep and robbing you of total sleep time.

• Set the room at a cool, comfortable temperature for sleep. Some people prefer warmer sleep environments than others, so when your team travels, try to find a roommate with a similar temperature preference.

Speaking of travel, this can raise several challenges for athletes' sleeping patterns, especially when a trip involves crossing multiple time zones. It may take several days for circadian rhythms to adjust to the new daylight hours and sleep/wake times of a different time zone, so teams should take this into account when planning trips. (For some specific advice on adapting to time zone changes, see "Time Travel" at the end of this article.)

MUCH TO GAIN
Serious athletes will do whatever they can to get better at their sport. That's why they come early to practice and stay late, wear themselves out in the weightroom, and spend countless hours on their own in the gym or on the field, honing their skills to gain even the slightest edge against future opponents. It's your job to help them realize that devoting more time to sleep isn't being lazy or slacking off--it's enlightened self-interest.

Luckily, the research suggests that a moderate sleep debt can be cured with just a few consecutive nights of prolonged sleep, and once athletes develop better sleep habits, the performance advantages should show themselves fairly quickly. Well-rested athletes may soon find they're recovering faster after workouts, performing sport skills with greater accuracy and proficiency, enjoying improved cognitive and motor function, and feeling better all day long.


Sidebar: TIME TRAVEL
It's the opportunity of a lifetime: One of your teams has been invited to play in a tournament in Hawai'i, or is finally taking that trip to Italy the coach has talked about for years. After months of planning, anticipation, and excitement, the plane touches down and the athletes can't wait to put on their uniforms and compete. But when they meet for their first morning practice, they're groggy, out of sync, and tiring much more quickly than usual. Jet lag has set in.

Adjusting to a new time zone can be a major challenge for teams that do long-distance travel, and unless there's some advance planning, a dream trip can turn into a performance nightmare. Here are some pointers for making a smooth transition:

• Whenever possible, adjust practice and workout times to accommodate athletes' internal clocks. For instance, if you usually practice at 3 p.m. in Boston and you're traveling to Rome (which is six hours ahead), try holding your first practice at 9 p.m. As your schedule allows, gradually move practices, workouts, and even scheduled games "backward" to ease players into the new time zone and minimize circadian rhythm disruption.

• Athletes may be tempted to take long naps the first few days after arriving if they're tired out by jet lag, but this should be discouraged. It will only delay adaptation to the new time zone, as the body attempts to stick to the sleep schedule it's used to back home. If a player must nap, a short doze of around 10 minutes can have some restorative effects without delaying time zone adaptation.

• Departure and arrival times can play a major role in jet lag, so try to schedule flights that will allow players to get a full night's sleep their first night in the new time zone.

• Tell athletes to avoid caffeinated foods and beverages on the plane if the team is arriving at its destination in the evening. Caffeine affects individuals differently, but for many, it can make falling asleep difficult for several hours after consumption.

• Remember that jet lag is worst when flying eastward, so a trip to Europe will require greater adjustment than a trip to Hawai'i, even if the actual difference in hours is the same. That's because you "lose" hours when you travel east, winding the clock forward instead of backward. A westward trip may even afford an opportunity for players to resolve minor sleep debts by using the "gained" hours to get a great night's sleep upon arrival.


Sidebar: ADDRESSING APNEA
Sometimes, an athlete's sleep problems aren't caused simply by stress, neglect, or a busy schedule. Sleep apnea is a serious and possibly even fatal condition in which a person stops breathing while asleep, usually because their airway is obstructed. It can affect anyone, but three of the main risk factors are being male, being overweight, and having a large neck circumference--all of which describe most football linemen to a 'T.'

A 2003 study in the New England Journal of Medicine made headlines when it looked at 300 NFL players and found that 34 percent of the linemen suffered from sleep apnea. Awareness was further raised the following year when 13-time all-pro Reggie White died unexpectedly in his sleep, and the medical examiner's report said apnea may have been a contributing factor.

So when Middle Tennessee State University Athletic Director Chris Massaro proposed earlier this year that Head Football Coach Rick Stockstill send some of his linemen to participate in a sleep apnea study, it didn't take much convincing. "Some of my friends had been tested for sleep apnea, so I was familiar with it," says Stockstill. "I thought it would be a great idea for our bigger guys to get tested."

The Sleep Centers of Middle Tennessee selected 16 MTSU linemen who displayed physical characteristics consistent with elevated sleep apnea risk. After analyzing their breathing during sleep, researchers led by Clinical Director Brian Wind, MD, found that two of the linemen suffered from severe sleep apnea, and 10 others had borderline or mild cases.

Sleep apnea causes the neck muscles to relax during sleep, allowing the soft tissue in the back of the throat to collapse and block the airway. This can halt breathing for 10 seconds or more, often causing the sleeper to snore loudly or wake up gasping for breath. These frequent interruptions in sleep can lead to daytime fatigue, morning headaches, and reduced blood oxygen levels. Untreated apnea can lead to high blood pressure, irregular heartbeat, and increased risk of stroke, heart disease, and even type 2 diabetes.

For treatment, the linemen diagnosed with severe sleep apnea were given Continuous Positive Airway Pressure (CPAP) machines, which use a mask or nasal tube to continually force air into the throat to keep the airway open. Wind says the mild cases can be treated more simply, through weight loss and teaching the athletes to avoid sleeping on their backs.

"We feel pretty good about being able to step in and help these guys," says Wind. "The two athletes with severe cases most certainly would have had long-term consequences in both health and quality of life."

"If a kid sleeps for three or four years with apnea and doesn't do anything about it, eventually his heart is going to wear out. He can pass a physical and appear to be in great shape, but over time, his heart is just not capable of handling the load it's given," says former MTSU Head Athletic Trainer Joe-Joe Petrone, who recently moved to Auburn University. "The two athletes who are now on the [CPAP] machines have reported that they feel better during the day, and that they're more alert in the classroom and during lifting and running."

How do you decide who in your program should be tested for sleep apnea? "The two big screening questions are, 'Do you snore?' and 'Are you sleepy during the day?'" explains Wind. "There are other signs as well. If you have a 19- or 20-year-old with high blood pressure, that's a major red flag that they should be checked out.

"In putting players through the screening process, if nothing else we're educating them about sleep apnea," Wind continues. "I'd be willing to bet that 80 to 90 percent of these guys will have sleep apnea to a severe degree when they are done playing football. Ex-football players often see their weight shoot up once they stop playing and working out. By testing them, at least a seed has been planted so that when the symptoms kick in later in life, they say, 'I remember learning about what this might mean.'"

Stockstill believes sleep apnea testing--which is fairly inexpensive and available at many sleep centers and clinics around the country--should become standard practice for athletic programs. "If you deal with bigger guys, you're crazy if you don't perform sleep apnea tests," he says. "It's not only good for them as athletes, it's also an opportunity to impact their whole lives in a positive way. You might even save someone's life."

--Kyle Garratt
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