Filed under: Sleep
Our bodies know when to sleep thanks to “circadian rhythms,” which are regulated by our brains on a 24-hour cycle. Circadian rhythms are linked to core body temperature, so ideally you should always sleep between 0300 and 0500, when your core body temperature is lowest and your performance abilities are at their lowest. Keep in mind that your individual circadian schedule is based on where you are and takes cue from environmental factors such as the sun and from social patterns. When crossing time zones, your internal clock needs time to adjust, which can take several days. Factors that influence this adaptation are:
- how many time zones are crossed, and
- whether you fly eastward or westward—the former takes longer to adjust.
Keep in mind that, in order to make up sleep or to adjust to a new zone, the best times to sleep are between 0300-0500 or 1300-1500.
For tips on how to improve your quality or length of sleep check out HPRC’s Sleep Optimization section, and for information on how sleep loss impacts all of the areas of Total Fitness check out HPRC’s Overview on sleep loss.
Think about this: Not getting enough sleep has a serious impact on how and what you think—your memory and concentration suffer, as do your awareness of your surroundings and your reaction time. Sleep loss affects your ability to make good decisions and puts you on edge, making you susceptible to your emotions. There’s more: Sleep loss also affects your ability to think positively and solve problems effectively. All of these are key factors in managing stress. Making good decisions now reduces your stress over the long term, and this can be compromised when you’re not at your peak. Bottom line: Focus on getting enough sleep to help you manage your stress.
For more on how to get better sleep, check out HPRC’s Mind Tactics information on sleep management. For how sleep loss affects all the areas of fitness, check out the HPRC’s Total Force Fitness article on The impact of sleep loss on total fitness.
Although there are individual differences in sleep needs, most people need seven to eight hours of sleep at night to function optimally, and anyone who sleeps only four to five hours each night will experience some loss of performance. Sleep loss hinders your ability to accurately interpret the emotions of others and identify what they’re feeling. Specifically, sleep loss impacts your ability to interpret the emotions anger and happiness expressed in the faces of others, making it difficult to interact effectively and communicate clearly with the people around you, reducing one’s ability to maintain good relationships.
It’s been commonly thought that exercise can ward off the effects of sleep loss, but it turns out that exercise only mitigates sleepiness and fatigue for an hour and doesn’t seem to have any effect on boosting performance throughout the day. Although regular exercise—both strength training and high-intensity endurance—does help you sleep better, it can’t replace lack of sleep—only actual sleep will do that. The loss of sleep affects physical performance primarily by reducing your motivation to exercise—so, when thinking about your workout plan for the week, include a plan to get enough sleep.
For information on how to improve the quality and length of your sleep, check out HPRC’s Mind Tactics Sleep Optimization section. For information on how sleep loss impacts other areas of fitness, check out the HPRC’s Total Force Fitness article The impact of sleep loss on total fitness, and for information on physical fitness check out HPRC’s Physical Fitness domain.
One thing all Warfighters need—and often don’t get enough of—is sleep. This essential restorative affects, and is affected by, virtually every aspect of total fitness. HPRC has already taken a look at the basics of sleep in “How Much Sleep Does a Warfighter Need?” Now we take a look at how it relates to mind tactics, stress management, relationships, exercise, nutrition, dietary supplements, and environment in a new review: “The impact of sleep on total fitness.” Insufficient sleep will make it difficult to concentrate, make decisions, solve problems, and cope with stress. It affects your relationships with others as well as your physical endurance. Exercise, nutrition, and environment—especially time zone changes—affect how well you sleep. Some dietary supplements may enable you to function with little sleep for a while, but in the long run they can’t substitute for a regular night’s sleep. Sleep significantly impacts ALL areas of Total Fitness and can greatly enhance or undermine your ability to be fit and resilient.
Besides keeping you healthy and fit, exercise has another important benefit. According to a news release from Oregon State University, a study conducted on more than 2,600 men and women between ages 18 to 85 found that individuals who exercise for 150 minutes a week at a moderate to vigorous level experience a 65% improvement in sleep quality. In addition, active people experienced less daytime sleepiness than those who are inactive. These findings appeared to be across the board—subjects experienced better sleep regardless of age, weight, and other health habits. For many, regular physical activity can be an effective, non-pharmaceutical alternative to improving sleep and concentration levels during waking hours.
The study, which was published in the December 2011 issue of Mental Health and Physical Activity, adds more evidence to the amazing body of research that demonstrates the importance of exercise for overall health.
Have you ever had one of those days that never seemed to go well, from the minute you heard the alarm clock go off? Maybe you didn’t have time for breakfast, forgot your laptop at home, lost your temper when someone cut you off on your way to work, replied to an e-mail in a way you really wished you hadn’t, ate poorly all day, couldn't concentrate at work, and then couldn't find the energy to go the gym?
Ask yourself how you slept the night before. One factor that can contribute to bad days is lack of sleep. Not getting enough sleep is all too common in the military and across the country—it’s often looked at as the price you pay to get ahead. Some sacrifice sleep for social activities at night—web surfing, e-mailing, watching TV, playing video games, or one more drink out with buddies—which further worsens the issue.
Bottom line: Not getting enough sleep is pervasive throughout all ranks and has major negative impact on your health, relationships, and career. The effects of sleep loss affect performance in much the same way that alcohol intoxication does. So coming to work deprived of sleep is rather like coming to work drunk. Your interactions with others and your job performance suffer—which has a huge impact on safety. Losing sleep isn’t sustainable for the long run.
But the damage doesn’t stop there. In fact, sleep loss has a ripple effect throughout virtually every aspect of health and wellness, including your physical, emotional, social, family, and spiritual well-being (see the five program components of Comprehensive Soldier Fitness here). It increases your risk of disease and harms your social relationships and possibly your professional reputation.
Sleep deprivation can be a byproduct of mission demands, of course. In the military, sleep loss is sometimes used on the battlefield as a weapon, wearing the enemy down through non-stop engagement. The problem is that this strategy affects our own Warfighters, too. Senior leaders are cautious in employing this tactic, and it’s used only for specific, organized, orchestrated periods of time, allowing for a full rest and recovery before massive errors occur that can cost lives.
Where many of us go wrong is thinking this type of sleep schedule is normal and maintaining it post-deployment. Most people aren’t able to tell when their state of mind—alertness, mood, concentration—has been compromised by lack of sleep until gross errors are made.
I believe sleep is the single most vital wellness function we do every single 24-hour period, and yet it requires no treadmills, no weights to be lifted, no personal trainers, and not even special clothes. It has dramatic implications for your entire body and sets you up for optimization everywhere else. Sleep is commonly overlooked at the doctor's office because physicians (including myself) don't understand exactly how it works, and in fact, there is no standardized medical test to see if you are getting enough sleep. But that’s no reason to ignore the health treasures afforded to those who get a great night's sleep on a regular basis.
On average, we spend 20-25 years of our lives sleeping, and five to seven of those are spent the critical dream periods known as "Rapid Eye Movement." REM periods occur at regular intervals throughout a night of good rest (when not impaired by alcohol, caffeine, or other drugs). Unfortunately, many of us look at this time as wasted, yet it can be some of the most glorious "unconscious" time to improve our health!
During REM periods, your brainwave patterns register signals much like those produced when you are awake and concentrating. During sleep you also secrete hormones that repair tissue and renew microscopic damages to cells and organs before they develop into bigger problems. In fact, you actually concentrate and focus for several hours throughout a good night's rest as you repair your body! Your brain, the center of all health, is exercising while you lie quietly in dreamland! When you destroy the quality of your REM sleep, the result is poor performance, inattention, obesity, hormonal imbalances, poor appetite, lack of normal growth, high blood pressure, poor interpersonal skills, no energy for the gym, possibly diabetes, and more.
Getting enough sleep means you are more likely to live longer, experience less disease, retain information better, perform better, and get more out of your workouts. You will be more patient with others, less demanding and prone to anger, and able to optimize all aspects of human performance, including your family relationships. For more about getting enough sleep, visit the HPRC’s Sleep Optimization page. Don't overlook the simplicity of a good night's rest.
Although regular exercise can improve sleep (see this HPRC article), your workout time may be putting you in a less-than-ideal state for a good night’s rest. Exercise not only makes you more alert but also raises your body temperature, both of which can make falling and staying asleep more difficult. To create healthy sleep habits, the National Sleep Foundation (NSF) recommends that you finish your workout at least three hours before you go to bed. View more healthy sleep tips on the NSF website.
If you’ve ever switched times zones, even as little as one hour, you may be aware that it can disturb your sleep and even disorient you in the following days. Without taking any medicinal countermeasures, you can typically adapt to your new time zone with about one hour of extra sleep per day after arrival (depending on with direction you’re traveling). However, some operations require that you be able to perform within 24 hours of arrival. To better prepare and adjust to your new time zone, use these strategies:
- One week before you travel, adjust your sleep schedule about one hour per night towards the time zone you are flying in—i.e., if flying eastward, go to bed and get up earlier; if flying westward, sleep later.
- Before you take off and while on the aircraft, eat light snacks, avoid alcohol, and stay hydrated (with water).
- On the aircraft, make sure that you are comfortable and able to nap before you arrive at your destination.
- Setting your watch to your new time zone as soon as you board your flight will help you transition.
- Take a short nap when you arrive at your new location, if you’re able to do so.
For more information, read the sections on jet lag in this article on sleep rhythms.
Misinformation abounds regarding ideal nap lengths for optimal cognitive performance. You need sleep to function at your best. If you do not get the recommended seven to eight hours of sleep a night, then napping can help. Learn more in