Features Research
A wake-up call to better sleep

Although sleep has been a human preoccupation through the ages, the scientific study of sleep is surprisingly recent, and sleep medicine is an even newer area of study. The book Le Problème Physiologique du Sommeil, published by French scientist Henri Pieron in 1913, is viewed as the first examination of sleep from a physiological perspective. Dr. Nathaniel Kleitman, the “Father of American Sleep Research,” began his work in the 1920s. Basically, the current understanding of sleep health has been evolving over fewer than 100 years.

The reason for this lag in curiosity with regard to sleep, as compared to other areas of human health and activity, appears to be the historical view of sleep as merely an absence of wakefulness. Until the latter 19th century, prevailing theories postulated that sleep resulted from stoppage or suppression of brain function – through, for example, some inhibitory mechanism that “turned off” the brain – or that neurons were paralyzed during sleep and could not communicate with each other. It is not surprising, given the belief that the brain is simply not working while a person sleeps, that interest in what transpires during sleep remained at a low ebb for so long.
Although modern sleep science is still young and contains many open-ended questions, the current view of sleep has completely overturned these earlier ideas. Sleep is now understood to be a highly regulated neuroactivity during which processes essential to life and health take place. It is perhaps ironic that scientific understanding of the importance of sleep is expanding rapidly in an epoch when cultural trends toward devaluing the need for sleep are very strong. But in fact, new information is being released all the time about the short-term and long-term health implications of insufficient sleep.
It is also very interesting that massage has been emerging as a powerful sleep-promoting tool. Massage therapy’s impact on sleep is a fairly well-researched subject, representing one of the biggest areas of focus on massage therapy effectiveness in the medical-scientific literature. However, we as massage practitioners have traditionally not learned much about the subject.
The purpose of this two-part article is to make valuable information about massage therapy and sleep known to massage therapists. In this first part, sleep, itself, and its role in health will be discussed. In part 2, the focus will be to describe the components of high quality sleep, and the evidence supporting that massage therapy helps to achieve them.

SLEEP DESIGN AND CYCLES
Sleep is divided into two principal stages: REM (rapid eye movement) and NREM (non-REM). Over the course of a normal adult sleep, 75-80 per cent of sleep time is spent in NREM and 20-25 per cent in REM.

NREM sleep occurs in levels of increasing “depth” that, in the simplest sense, can be divided into light sleep and deep sleep. As NREM sleep depth intensifies, eye and body movements diminish to almost none, body temperature decreases (essential for certain metabolic processes) and blood flow to the brain lessens substantially. The body “descends” into a strong parasympathetic state with slow, stable vital signs.

NREM sleep, particularly deep sleep, is crucial to nutrient utilization, tissue maintenance routines, glucose/glycogen regulation and production/release of glandular secretions and hormones, as well as functions such as immune resilience, blood pressure stabilization and injury healing. There is also brain maintenance work done: for example, increased protein synthesis in the central nervous system, “cleaning up” of redundant or excess synapses and updating of factual memory. To list just a few of many possible examples of hormone production and release ramifications of insufficient deep sleep: the neurotransmitters needed for mood stability and pain modulation drop in volume; growth hormone is not released in sufficient quantities; metabolic rates are not properly controlled; and sexual interest and fertility can be impaired through reductions in sex hormone release.

REM sleep is characterized by intense brain activity during which cerebral blood flow increases and the occupations and challenges of the day are processed neurologically. The brain is operating in an energy state similar to that of being awake. As the brain “works,” physiological manifestations occur that include bursts of rapid eye movements and irregular patterns of blood pressure, heart rate and respiration. The majority of dreaming occurs in REM sleep. In order to prevent potentially dangerous body movements from taking place as an automatic consequence of such brain activity, this stage of sleep is accompanied by sleep atonia (pseudo-paralysis), a skeletal muscle inhibition state like that induced pharmacologically during surgery to prevent unconscious patients from lashing out or recoiling physically.

REM sleep is vital to brain development and to learning. Individuals who are learning a new skill during the day spend more time in REM sleep that night. Infants spend about 50 per cent of their sleep time in REM (premature infants even more). REM sleep is also essential for limbic system processing and restabilization – we are all familiar with the benefits of “sleeping on it,” and with the emotional shakiness that comes from insufficient sleep.

Deep sleep and REM sleep are the two major workload times in a sleep cycle, and although it is overly simplistic, one could say that deep sleep is “tissue needs time” and REM is “brain processing time.” Each constitutes 20-25 per cent of a normal adult’s night’s sleep.

After the age of three, normal NREM and REM sleep segments occur in cycles as illustrated in Figure 1.

The NREM-REM cycle rotates every 90-110 minutes. Deep sleep stages are proportionately longer in the first half of a night’s sleep. As the night progresses, deep sleep portions shorten and REM portions lengthen. It is significant to note that when people get an hour or two less sleep than they should, it is the long, final REM segment that is sacrificed. While it can function as a stress reducer, napping cannot compensate for a shorter night’s sleep because the nap cannot recoup the REM stage that occurs at the end of a major sleep. In other words, the person who naps for 1.5 hours and sleeps for 6.5 at night is still going to be REM sleep deprived.

There are homeostatic factors at work in sleep, however. It is possible to make up for shortened sleep stages on a subsequent night. Just as some sleep segments can be increased according to need – for example, REM sleep in a student learning new skills – there is scope for adjusting the relative length and duration of specific stages over the course of a full night’s sleep. In this way, individuals can be underslept for a day or two and then “pass out” for an unrestricted recuperative sleep. (It should be noted that the ability to do this successfully diminishes with age.) The health issues that arise from sleep deprivation are the result of not ensuring, or being unable to have, this recuperative type of sleep to compensate for losses over time.

Sleep is also connected to the body’s circadian rhythms and is entrained to the alternation of light and dark in our external environment. Melatonin, a hormone produced by the pineal gland as part of the circadian system, is one of the most important sleep promoters. Its maximal secretion time is at night, stepping up at dusk and increasing as the person segues toward sleepiness and through the first half of the night’s sleep. Another area of concern for sleep specialists is the extent to which people now interfere with normal circadian responses by over-utilizing light sources at night, especially backlit ones, such as computer monitors, close to the eyes.

SLEEP REGULATION
The hypothalamus is the key sleep-regulating area of the brain. Aided by various chemical and neurological inputs, the hypothalamus:

• directs the homeostatic aspects of sleep
• integrates with and modulates circadian processes
• harmonizes sleep/wake cycles with autonomic functions such as body temperature regulation and sympathetic versus parasympathetic status
• ensures efficient transition between asleep and awake states

It is true that there are “morning” and “night” people – this is referred to as chronotype. There are differences in the way sleep is regulated in the two groups, including timing of peaks and lows in their body temperature.

It is also true that there are individuals who need less sleep than average (and some who need more). Experts are adamant that most people who believe they are doing well on shorter sleep times are kidding themselves, stating that only when a person falls asleep and awakens naturally – without needing an alarm – and does not have daytime sleepiness or any adverse indicators pointing to insufficient sleep, could he or she be seen as naturally being a shorter sleeper. It is also current expert opinion that the human body cannot evolve to handle receiving less sleep. One’s sense of doing well on shorter sleep times is apparently aided by the same type of denial mechanism that allows people to feel much more functional than they actually are when drinking alcohol.

Figure 2 shows the average required amount of sleep according to age. Experts are particularly concerned about the current trend toward undersleep in toddlers and teenagers, who are often sleeping fewer hours than they need, and the prevailing myth that seniors need less sleep. Adverse physical and mental health findings correlate very strongly with short/poor quality sleep in older people; the very healthy elderly almost always demonstrate good night-time sleep patterns.

HEALTH IMPLICATIONS OF SLEEP DEPRIVATION
For babies, children and teenagers, adequate sleep is essential throughout the stages of their growth and maturation. The physiological processes of brain and body tissue development demand adequate sleep, as do emotional resilience, ability to learn and perform in school and capacity to establish normal eating and sleep habits. Underslept children often display signs similar to learning disability and/or mood disorder, leading to frequent misdiagnoses. More recently, scientists have started to assess inadequate sleep in the pregnant mother as a source of development issues in babies.

Recent research indicates that individuals who sleep less than six to seven hours per night die younger (reported in Stein, 2005). Although the reasons for this are not fully understood, there are powerful new facts about the correlation between chronic undersleeping and major health concerns. For example, sleep deprivation promotes obesity by influencing the release of appetite-regulating hormones. It is also linked to development of hypertension, heart conduction abnormalities and vascular changes associated with atherosclerosis and thrombosis, making it a big risk factor for heart attack and stroke. Combined with the above factors, disruption of glucose/glycogen regulation makes chronic sleep deprivation one of the top five risk factors for developing Type 2 diabetes.

We are quite familiar with the idea that being underslept makes us more susceptible to getting colds and flus but may be less cognizant that longer-term impacts of a less resilient immune system, coupled with pro-inflammatory effects and impaired hormonal regulation, have led to an awareness of sleep deprivation as a promoter of cancer, especially hormone-sensitive cancers such as breast and colon.

There is also a great deal of interest in the relationship between sleep and pain. Because key pain-regulating chemicals are produced during deep sleep, pain neuromodulation is impaired by sleep deprivation. The emotional capacity to handle pain is also impaired. Pain levels decrease following a restorative sleep regardless of other treatment interventions. While we tend to think of such effects as secondary in the pain cycle, it has also been found that people who are deprived of Stage 4 NREM (deepest sleep) develop musculoskeletal pain as a result (Davis, 2003).

There is also a connection with mental health: throughout the lifespan inadequate sleep is associated with increased depression and anxiety, and being underslept is a significant trigger for people with mood disorders.

In general, spending less time sleeping means spending less time in “digest and restore” mode, promoting digestive problems, stress-related health changes and poorer quality body tissue. Insufficient sleep is known to increase proneness to soft tissue injury, for example, and to reduce the speed and quality of tissue recovery. At a recent conference, one sleep expert argued that sleep should be monitored by health professionals as a vital sign, with the same vigilance as blood pressure, diet and exercise.

In Notes on Nursing, Florence Nightingale wrote “sleep is all-important to the sick.”

This poses some interesting questions for massage therapy treatment planning: are we asking enough about sleep as part of our history taking and regular check-ins with clients? Shouldn’t we be making sleep promotion a primary aim of treatment, especially following surgery, illness and injury? Shouldn’t we routinely be considering a client’s sleep status before doing tissue-altering work? And so on.

In the second instalment of this article, we will take a look at what constitutes good quality sleep and at the evidence for massage therapy as a highly effective sleep promoter.

Note: References for this first instalment will be included at the end of Part 2.

Debra Curties is a graduate of Sutherland-Chan School & Teaching Clinic in Toronto and presently works there as executive director and longtime instructor of pathology and clinical theory. She has been involved in multiple professional organizations in Canada and the U.S. and is a recipient of the Ontario Massage Therapy Association’s Meritorious Service Award and the AMTA COS Meritorious Service Award. A co-founder of Curties-Overzet Publications, Debra is the author of Breast Massage and Massage Therapy and Cancer. She also travels extensively teaching continuing education courses for massage practitioners.