Υπνος και υπεραποστάσεις

Posted: 17 Dec 2013 03:00 AM PST

Ultrarunners are always looking for ways to improve. We strive to improve our time over a certain distance, improve our strength, improve how we recover, and improve our flexibility (well maybe not all of us). But do we look at our sleep for improving our performance? Many of us work hard Monday to Friday, often putting in irregular hours or doing shift work. We may want to “catch up for lost sleep” on the weekend, but instead, we skip the chance to “sleep in” on Saturday or Sunday so we can get an early start on our long runs in the hope we can spend more time with family and friends later in the day. Today’s ultrarunners often don’t fit the typical profile of full-time athlete.  Instead, we come from a wide variety of backgrounds and professions which demand that we fit our running into an already packed schedule that includes actively managing family life, social interests, business obligations, and exercise, whilst armed with a laptop, smart phone, and a cup of coffee. And with so much to do every day, the first thing that is often sacrificed is sleep.  But is this a good idea if peak running performance is the goal? Research in the sleep science field suggests that maybe it isn’t. In fact the growing body of research coming out of a number of reputable universities around the world says sleep is a lot more important than previously thought. Let’s take a look at a few areas where we now know about the relationship between human performance and sleep.

Issues around race start times

Start times vary quite a bit depending on where the race occurs, how long it is, and how many runners are expected, and the body responds to these timing differences in several ways. To understand the effect of different race start times we must first think about circadian rhythms. Circadian rhythms occur within every human. Circadian is derived from the Latin word “circa” meaning “about”, and “dia” meaning “day.” Circadian rhythms happen over a 24-hour period, and they affect a lot of different body functions like temperature, hormone levels, energy, and appetite.  For example, as we wake in the morning, between 06:00-09:00, cortisol and body temperature increase. Then, in the afternoon, between 13:00-15:00, there is a circadian dip often referred to as the post-lunch dip. This may explain why we often find it difficult to concentrate at work after lunch, and this difficulty explains some of the afternoon safety and quality issues in workplaces. “Siesta” in Latin cultures is designed to allow people to relax during this low point and also to avoid midday high temperatures, but the siesta is rapidly becoming a thing of the past in today’s busy world.

Another result of the circadian rhythm occurs in the evening, between 17:00-20:00, when we go through a phase called the “forbidden zone.” This is a time when we find it most difficult to sleep and generally when we show our greatest cardiovascular efficiency and muscular strength. This may explain why some days when we are at work, all we can think about is getting home to sleep because we are so tired, but when we get home we get a “second wind” and become energetic and awake. It also explains why if you’ve ever tried to go to sleep earlier than usual at night to prepare for an early-morning wakeup the next day, you instead find yourself just lying in bed staring at the ceiling for 2 hours. So, in today’s world, this forbidden zone seems to cause us nothing but trouble, but there are reasons it exists. Some researchers in the anthropology field believe that the forbidden zone may be part of the planet’s natural cycle, and that humans evolved this way so that they could be hyper-alert to the dangers posed by predators that came out at night to hunt.  The start times of some of today’s races actually take advantage of this forbidden zone. An example is the Ultra-Trail de Mount-Blanc (UTMB) run which starts in France at approx. 16:30 when some 2,300 people take off to complete the 166km mountain through 3 countries.

But while it might be good to start a race or train for a race in the late afternoon/early evening, early-morning start times can spell trouble. Between the hours of 02:00-06:00 we experience a circadian low which is fine most of the time since we’re asleep.  Unfortunately, as ultrarunners we often have to wake-up during this time to get our training runs in or to start a race. During this circadian low-point we find it extremely difficult to stay awake as anyone who works shift work can tell you.  This is the time during which drowsiness, sore eyes, yawning, inattention, low energy, and perhaps even micro-sleeps commonly occur, and all of these problems of course make early race starts difficult also. For those who have stepped on the start line at Leadville at 04:00, you most probably struggled through a 2 a.m. wakeup or you might have even skipped pre-race sleep altogether due to nerves.

Whether you are waking up at this low circadian point or trying to stay awake while running a long race that started the previous day, the period from 02:00 -06:00 is a problem.  This is the time when we start getting cold because this is when we experience our lowest core body temperature .Our decision making is affected as we have most likely been awake in excess of 12 hours and maybe up to 24 hours. Our ability to rationalize and stay on track becomes increasingly difficult. Thoughts and feelings of self-doubt increase, DNF at the next checkpoint creeps into the words we speak.

Author note (Ian) I myself was a victim of this in 2012 at Leadville with a DNF at the last checkpoint (May Queen 88 miles) just before sunrise. In 2013 avenged this DNF with a finish at Leadville.

Contrary to common belief or hearsay, you cannot force your body to be awake and effective during this time, and while it is possible to adjust your circadian rhythms, it is a slow process that takes many days and concerted effort. It’s also important to know that even people who learn science-based techniques to readjust their rhythms can experience short or long-term health issues such as gastrointestinal distress, heart disease, increased body weight, and diabetes due to consistent disruptions to the body’s internal clock and constant bouts of sleep restriction or sleep disturbances.  On average, people need 7-9 hours of sleep per night, and failure to get this amount has many negative effects.

So what can we do in advance or prior to a race to minimize all of this?

Strategies around reducing sleep debt prior to an event

Sleep is like the fuel in a fuel tank – what you take out must be replaced. Just like with our diets, we measure calories in/calories out over a day to maintain a consistent energy balance. Sleep is no different. If you do not fill up your sleep tank or reservoir, you decrease your probability of success and increase your probability of failure and increase personal risk because you are running out of “fuel”. In our running, insufficient sleep leads to a decrease in energy levels, poor training runs, or poor times across distances when we know we can do better. At home we may have trouble staying awake, or we might nod off easily when watching a movie or TV with our family or friends because we’re not refilling our sleep tank enough every day. In some cases this chronic sleep loss even causes depressed feelings, mood swings, and irritability.

In the book “Running with the Kenyans “ by Adharanand Finn, he identifies an interesting aspect of Kenyan culture and running training that is not practiced well with most people—GETTING ENOUGH SLEEP! Finn says that the Kenyans sleep up to 14 hours a day whilst training. Evidently, they get the point that sleep is vital for physical and mental recovery and the release of growth hormones (which are important for muscle building and recovery). In other recent reports about the importance of sleep and athletic performance, scientists have found support for the Kenyan sleep habits.  Cheri Mah at Stanford University in the USA has conducted several studies on collegiate players.  She found that extra sleep had a significant impact on the speed and performance of swimmers and basketball players.

Jet Lag and international travel

Many of us dream of traveling to compete in overseas ultraruns such as the UTMB, Leadville, Western States, Comrades and many more. In general to get to these events, we have to fly long haul (greater than 4 hours), and when we get where we are going, we feel the mismatch between the body’s internal clock and the local time. This is commonly called Jet Lag. So what’s actually happening? Our bodies are set to the time zone we are living in based upon natural light exposure and external factors such as the time on the clock, meal times and other social cues. For every time zone you cross it can take on average of 24 hours to adjust to crossing each time zone, and thus, it can take several days to readjust after crossing several time zones. For example a full readjustment after traveling from London (GMT) to Singapore (GMT +8) can take up to 8 days. And the direction of travel makes a difference too. Ideally trips should be scheduled to keep traveling in a westerly direction if possible, because readjustment after westward travel is quicker and easier. Here are some actions that will that will help when flying for races

  • Exercise is important to help your body adjust to the local time zone. This will help to revitalize when you arrive and reset your body clock. You should exercise during daylight hours, particularly in the early hours of the day for at least 30 minutes
  • Avoid alcohol as a solution to sleep problems because although it may help you to get off to sleep, you will not sleep as well during the night.
  • Minimize continuous use of sleeping tablets since they can become a habit, giving you more problems than temporary jet lag especially if they are taken at the wrong time
  • Melatonin may help to re-set your body clock. If you elect to use melatonin, take it just before your planned sleep time.
  • For short trips, stay on home time If you are away from home for a only a day or two, try to eat when you would usually eat at home, try to sleep when you would usually sleep at home, and try to not go outside and get sunlight exposure during times when it is dark at home.
  • For longer trips, change your schedule as soon as possible, if you are away for more than two or three days, start using the time at your destination as soon as possible (even before leaving home).
  • Change your watch on the flight. Try to eat and sleep on the plane at times when you would eat and sleep at your destination. The earlier you start, the easier it will be.
  • After arriving in the new time zone, try to avoid any sleep before the new local bedtime so that you can more easily sleep during the night.  Force yourself to wake up at the normal local wake-up time, and go outside to get sunlight exposure.

So how does altitude affect your sleep and your performance?

One of the earliest studies on the effects of altitude took place in 1970 in the Antarctic whereby elevation and barometric pressure results in an environment with an altitude of 5000m/16,404 ft.

At these high levels people may experience disruption to stage 3 and 4 sleep and more sleep arousals. Total sleep time in many people remains unchanged , rather it is the amount of time in each stage that changes. At altitude more time is spent in stage 1 and 2 sleep and less time in stage 3 and 4. If you live at sea level or low lying levels when you move up to altitude you may experience sleep arousals or disturbance in your sleep. Most common at altitude you may experience the following;

Periodic breathing –Cluster of breaths separated by intervals of apnea or near apnea

Apnea – Temporary cessation of breathing

Studies report variable daytime performance, sleepiness and fatigue One study by Salvaggio et al in 1998 Effects of high altitude periodic breathing on sleep and arterialoxyhaemoglobin saturation, Eur resp journal,12 :408-413 found that periodic breathing and sleep arousals went on for as long as 4 weeks when people were at an altitude of 5050 m/16,568 ft. In particular if you change altitude levels often.

Altitude related sickness can manifest itself in two conditions that may arise if you rapidly ascent to new altitudes. The first is AMS or Acute Mountain Sickness whereby you may experience loss of appetite, decreased mental effectiveness and experience insomnia .The other is HAPE –High Altitude Pulmonary Edema. This can occur in levels in excess of 2500m/8202 ft (Brill et al, When “High” Is not Very High: High Altitude Pulmonary Edema as First Manifestation of Sarcoidosis-Related Pulmonary Hypertension. High Altitude Medical Biology Dec13 (4) 2012)

Other strategies include to Live High and Train Low. This is whereby an individual will sleep at 3000 m/9842 ft by way of actual location or by means of an altitude simulation tent. Then during the day the individual will train at low levels. However it must be noted that there are a large number of individual differences.

At altitude you will dehydrate more rapidly .In some cases there can be pharmacologic type interventions that will assist such as benzodiazepines and acetazolamide used for sleep disturbances at altitude, a medical doctor should be consulted prior to taking these medications.

Caffeine use

If despite all of your efforts to get plenty of sleep and schedule your wake-up, training, and racing times optimally you still are not as alert as you need to be, you can rely on caffeine for a temporary energy burst.  Research shows that it is safe to consume up to 800-1000 mg of caffeine per day in individual doses of about 50-200 mg each.  A standard cup of brewed coffee contains about 100 mg of caffeine, and a cola contains about 40 mg of caffeine.  These are good options to start, but if larger, faster-acting doses are needed, try caffeine gum (usually 40 mg per piece) or caffeine tablets (usually 100 mg each). Caffeine is very rapidly absorbed from caffeine gum.

Caffeine takes about an hour to start working, and the effects last about 4 hours, so don’t consume caffeine too close to bedtime.  Also, keep in mind that while caffeine is a temporary way to overcome drowsiness from sleep loss or low-points in the circadian rhythm, caffeine is not a substitute for sleep and large doses can cause stomach problems, heart problems, trembling muscles, and nausea.   Caffeine should be used in moderation and only when needed most since chronic consumption of caffeine will make it less effective for those times when a caffeine boost is needed the most.

Actions to take away

So armed with this knowledge and wanting to improve our overall “human performance” in our ultraruns, what can we do? Following these 10 guidelines around sleep hygiene can greatly improve your sleep, your waking alertness, as well as your subsequent performance:

  • Have a regular sleep pattern. Try to go to bed at the same time every evening, and wake up at the same time every day.
  • Schedule time into your life to get 7-9 hours per night of sleep. Do it just like you schedule training runs, races and meetings.
  • Avoid TV, smart phones, laptops, and work for at least 60 minutes before sleeping, and get the “technology” out of your bedroom.
  • Try reading a novel or listening to relaxing music to help you sleep. Studies show this can be just as effective as a sleeping tablet.
  • Use your bed for sleep and intimacy only—working on the computer, talking on the phone, or checking your smartphone for messages once in bed is a bad sleep habit.
  • Make your bedroom comfortable and, if possible, keep the room dark and cool (64-74F/18C–23 C) to promote a good sleeping environment. Consider using an eye mask and ear plugs.
  • Don’t lay awake thinking and watching the clock. If you can’t sleep, try getting up and reading or writing but avoid TV, computers and the like.
  • If you consistently have issues sleeping, consult a sleep physician or consult your general practitioner because you might have an undetected sleep disorder.
  • Avoid waking up or scheduling training runs before 05:30, especially if you can’t reliably get to bed early the previous night. If you are time poor, consider running to work. Use lunch breaks to catch up on kilometers. Consider cross training to improve performance.
  • Avoid caffeine, alcohol and cigarettes for at least three hours before bed.

In conclusion, sleep must be actively managed like other aspects of health and well-being. Sleep well, eat right, and run hard!!!!!!

Ian Dunican is the Director of Sleep4Performance working with athletes to maximize performance. He is an Ultra marathon runner and a Jiu Jitsu student in Perth, Western Australia. You can contact Ian at: sleep4performance@gmail.com or keep up to date on his sleep4performance Facebook page

John Caldwell, PhD is the Science Adviser for Clockwork Research, Ltd in London where he serves as an internationally recognized expert in sleep & performance enhancement. He has published numerous papers and book chapters, and he has delivered more than 100 presentations and workshops designed to help people optimise their performance in real-world settings πηγή:irunfar.com