Sleep for Optimal Health

By Tony Boutagy

Humans spend roughly one third of their lives asleep. But somewhat disturbingly, it is estimated that only one fifth of the world's population enjoys perfectly healthy, restorative sleep. For the rest, sleep, just like health, is one of those things we take for granted until it causes problems.

As personal trainers we are involved with improving the quality of our client's health. This usually involves the prescription of cardiovascular activities, resistance training, flexibility exercises and a healthy diet. But rarely would a trainer give advice to their clients on how to improve the quality of their sleep. Australian health expert, Dr John Lang explains that in addition to tiredness there is a litany of health related problems that stem from poor quality or quantity of sleep. Lang writes, 'The four pillars of good health - eat well, keep fit, manage stress and don't smoke, should be expanded to include a good night's sleep. Make no mistake: sleep (or lack of it) can have more devastating health effects than the other four' (Lang, 2002).

Although sleep research is a relatively young science, investigations conducted over the past several decades has provided researchers with some very fascinating information on the nature of sleep and factors that improve or detract from a good night's rest. By better understanding the cycles of sleeping and waking, and by following some simple strategies to improve sleep quality, personal trainers are in a position to add further value to their client's health and energy.

The ultradian rhythm

Most people are familiar with the circadian rhythm, but what is less commonly known of is the existence of the ultradian rhythm. Humans experience 'mini-cycles' of melatonin secretion that operate within a 90-minute period. This 90-minute period between peaks of melatonin is called the ultradian rhythm. We usually experience the effects of this rhythm every time we are watching something on television that runs from, say, 8:30pm to10:30pm. You may notice that you are having trouble keeping your eyes open at around 10pm but you force yourself to stay awake until the end of the movie. But by the time you go to bed after 10:30pm, you have difficulty falling asleep, even though 30 minutes earlier you felt challenged staying awake! Dr Lang explains that what has happened is that you have pushed through the low point of your ultradian rhythm and are now on the 'upswing'. The next opportunity to get into some reasonably sound sleep may not be until 11:30pm (90 minutes from your last trough) (Lang, 2002). However, most of us usually fall asleep within a shorter period than 90 minutes at that time of night because our circadian rhythm has dropped so low at this point that you can sleep even at the peak of the following ultradian wave.

Because the ultradian rhythm continues through the day and night, it is partly responsible for the 'slump' in wakefulness that we experience at certain times of the day.

The circadium rhythm

The human body runs on a 24-hour cycle. The 24-hour cycle of waking and sleeping is termed the circadian rhythm (circa = about, ada = day). In order for us to keep time with the cycle of the sun each day our body has an internal timekeeper which controls waking up in the morning and going to sleep at night. This timekeeper, called our biological clock, consists of about 10,000 nerve cells near some of the main areas in the brain that control sleep and wakefulness. The controlling factor of the sleep/wake cycle is the hormone melatonin, which is secreted by the pineal gland in the centre of the brain. Studies have shown that our biological clocks are set every morning upon waking when we see light. Bright light shone on the skin and eyes cause the pineal gland to cease its melatonin secretion and release the 'waking' hormones into the system (Idzikowski, 2000; Lang, 2002).

Stages of sleep

Adult humans typically sleep between six to nine hours a night. During this time we travel through four or five separate cycles, each lasting approximately 90 minutes. These cycles are interspersed with brief periods of wakefulness, which we don't usually remember. Each of these four or five sleep cycles has in themselves five separate stages, which include two stages of light sleep (drowsiness and light sleep), two stages of deep sleep and Rapid Eye Movement (REM) sleep. Sleep, however, is not a linear phenomenon. When we are asleep, we do not progress continuously through the stages of sleep from light (Stages 1 and 2) to deep (stages 3 and 4) to REM sleep. Rather, we make journeys back and forth - through Stages 1 to 4, then returning to Stage 2 before entering our first period of REM sleep. A healthy adult's sleep is comprised of roughly 50% light sleep, 25% deep sleep and 25% REM.

As a healthy adult begins to fall asleep the muscles relax and the eyes roll beneath their lids. This is called Stage 1, or the Drowsiness Stage, and lasts only about 10 or so minutes. If disturbed during this time, people often deny being asleep at all, even though it is clear to everyone else that they were! During this time our brains appear to hover on the edge of awareness - where we may experience weird, dreamlike visions or the sensation of falling. These hallucinatory aspects of sleep are called hypnagogia. Once we pass through Stage 1 and actually fall asleep, we enter Stage 2 - light sleep. Healthy individuals will usually only spend 10 to 15 minutes in Stage 2 before drifting deeper into Stage 3 sleep.

Stage 3 and 4 are the 'deep sleep' stages, and if woken during either of these periods, we are likely to feel groggy and disoriented. The transition from Stage 3 to Stage 4 sleep also occurs relatively quickly. It is believed that Stage 4 sleep is the most important of all sleep stages, as it appears to take precedence over all other stages. That is, if we go without sleep for one night or more, our bodies are programmed to ensure that we eventually make up any deficit by spending more time in deep sleep at the expense of light sleep the next time we sleep. Interestingly, the amount of time spent in deep sleep appears to be the same for those people who are constitutionally short-sleepers (four to five hours per night) and those who are constitutionally long-sleepers (nine or more hours), both spending around two hours in total per night.

The final stage of sleep that we experience is where we do most of our dreaming and is called REM sleep (so called because our eyes move rapidly back and forth beneath closed eye lids). REM sleep is related to the ultradian rhythm and therefore occurs roughly every 90 minutes. The fascinating aspect of REM sleep is that when the electrical impulses of the brain are measured with an electroencephalogram (EEG), they resemble the activity made by our brain when we are awake. Despite this brain activity and the movement of our eyes during this stage, the muscles in almost all the other parts of the body (except those that are essential for sustaining life) become paralysed. Presumably we experience this paralysis as a safety precaution to prevent us from acting out our dreams. Similarly to deep sleep, healthy adults will typically experience a total of two hours per night of REM sleep.

Five steps to a better nights sleep

1. Go to bed and wake up at the same time every day, including the weekends;
2. Create a bedtime ritual before retiring at night (such as a glass of warm milk, shower, clean teeth, relaxing oil in an oil burner and 10 minutes of light reading);
3. Expose yourself to bright lights immediately upon waking;
4. Avoid the sleep destroyers (caffeine, alcohol, nicotine) up to ten hours before bedtime;
5. Avoid taking naps for longer than 20 minutes during the day.

Use your biological clock

British sleep expert, Professor Chris Idzikowski believes that one of the most important strategies to improving sleep is waking up at the same time every day, including weekends. It appears that our biological clocks are set to the exact time we wake up in the morning and exposure to bright light. Have you ever had the annoying experience of trying to sleep in on the weekend but still waking up at the same time you wake up during the week? Did you notice this happens naturally, without the alarm? This is your biological clock attempting to keep the sleep-wake cycle constant. If you ignored your body clock and enjoyed a few more hours sleep, did you feel better or worse, more alert and refreshed or less? Most people will attest to feeling worse after a sleep-in because our body clock anticipated rising at a certain time and adjusted the amount of deep sleep accordingly. Sleeping past this time disrupts the delicate sleep-wake cycle that we establish during the week, so somewhat counter-intuitively, we will usually feel less refreshed after more sleep.

Expose yourself to bright lights

Another way to improve the quality of our sleep is exposure to bright lights immediately upon waking. As mentioned above, sunlight (or bright lights if the sun hasn't risen yet) stops the secretion of melatonin and stimulates our waking hormones, making us feel alert more quickly. Similarly, dimming the lights as we prepare to sleep at night activates the pineal gland to release the sleep-inducing melatonin. This helps the body to prepare for sleep.

No meal within three hours of bed time

Sleep experts recommend having your last meal no later than three hours before you intend to go to bed. Eating increases our metabolic rate and causes our body temperature to rise, and the perfect time to fall asleep is when our body temperature is dropping. So it also makes sense that we should avoid making our last meal of the day too big. In addition, some research has shown that the mineral magnesium can significantly improve the quality of our sleep and leads to fewer awakenings. Several good sources of magnesium include green vegetables, avocadoes, bananas, peanut butter, nuts and seeds. On the other hand, some foods contain natural ingredients or additives, which have a negative impact on sleep. Monosodium glutamate (MSG) is known to cause digestive upsets, heartburn and headaches. MSG can be found naturally in mushrooms, carrots and some seaweeds.

Stay away from the 'sleep thieves'

There are three powerful compounds that stimulate or depress the brain, causing considerable detriment to the quality of our sleep. Sleep experts call these three the 'sleep thieves', and they are: caffeine, alcohol, and nicotine. Caffeine activates the wakefulness centres in the brain, making us more physically alert and not sleepy. Alcohol destroys our sleep architecture by reducing the amount of deep and REM sleep we experience. While nicotine also stops us from obtaining our required amount of deep sleep. To optimise the quality of sleep, researchers recommend avoiding caffeine and alcohol within ten hours of going to bed at night, and all health experts, sleep doctors or otherwise, urge us to cease all use of nicotine.

The role of sleep

While scientists are currently unclear of the exact reasons why we undergo different stage of sleep, they do understand the different processes that occur during each stage. During the two stages of deep sleep our body secretes growth hormone, which aids cellular repair and regeneration, immune function, bone density, connective tissue, muscle mass and asthma, while it is believed that the consolidation of memory takes place during REM sleep. In addition, sleep in general is fundamental to mending damaged blood cells, repairing the daily wear and tear on the body, restoring the efficiency of the brain, and is essential for our emotional and mental wellbeing. Also, in the early hours of the morning, the immune system manufactures the antibodies to combat the antigens (viruses, bacteria, toxins, etc) to which the body has been exposed the previous day. Compromised sleep impairs antibody development, which means that the immune system will be suppressed (Lang, 2002).

Research has shown that if we are deprived of sleep for one night we usually make up almost all the lost deep sleep on the following night (mostly at the expense of lighter sleep). Even if we are made to go without sleep - say, for two or more nights - practically the entire deep-sleep debt is recouped over the course of our next two or more nights' sleep (Idzikowski, 2000).

Having problems falling asleep?

American sleep expert, Richard Bootzin, developed a technique to help people who experience difficulty falling asleep. It is called the Bootzin Stimulus Control and involves the following strategies:

• Go to bed only when you feel sleepy.
• Keep your bed as a place for sleep only.
• If you do not fall asleep within 20 minutes, get out of bed and do something else.
• Return to bed once you feel sleepy (and get up again if necessary).
• Set your alarm to wake you up at the same time every day - and do not sleep in. 
• Do not nap during the day.

Check the thermostat

The temperature of the sleeping environment can have a profound effect on the quality of our sleep. Research has shown that 16ºC is generally conducive to restful sleep, while temperatures above 24ºC are more likely to cause restlessness.

A warm drink really will help!

As part of a bedtime ritual, many sleep experts recommend consuming a warm drink in the evening. You could try mixing a cup of milk with a teaspoon of ground cinnamon in a saucepan and simmering for a few minutes. Add honey to sweeten if desired. Alternatively, herbal teas are a popular choice with sleep therapists. Try mixing one or all of the following in any combination: hops, valerian, chamomile, passionflowers, skullcap or lemon balm. Steep the herbs in hot water for between 8 to 15 minutes and drink warm.

By using the knowledge of sleep cycles and applying some or all of these sleep-enhancing techniques, you are in a position to further assist your clients to experience a greater quality of health.

This information is reproduced courtesy of Australian Fitness Network.

www.fitnessnetwork.com.au