Sleep Across the Life Cycle

Debra A. Guerrero

Sleep is a vital component of health. Along with proper nutrition and physical activity, good sleep provides a foundation for physical and emotional wellness. For sleep to be “healthy,” it needs to be of sufficient duration and timing, and without abnormalities or disturbances (1). Sleep technologists must be well versed in the nature of human sleep across the life span. This knowledge allows technologists to compare the sleep and sleep habits of patients studied to what is expected for their age group. Sleep health education is an important component of the sleep technologist’s core job responsibilities. The role of the sleep technologist is expanding with a new focus on patient education and therapy management. Technologists with specific education and a certification in clinical sleep health are assuming a larger role in providing sleep hygiene and disease-specific education for patients with sleep disorders and assisting in the management of their therapies. Caring for patients at all levels includes a discussion of basic sleep health. Questions relating to sleep needs and basic sleep hygiene practices are routinely discussed in sleep centers, often during polysomnography hookup procedures. Every patient interaction is an opportunity for sleep technologists to enhance patient knowledge regarding the importance of sleep.

SLEEP CHARACTERISTICS

Sleep is a state of being unaware of and unresponsive to the outside world that is immediately reversible (2). Resting with eyes closed in a recumbent position in darkness may look like sleep, but there is no disconnection from the surroundings. Likewise, coma or a state of unconsciousness is not sleep. A person in a coma may be disconnected from the outside world as if asleep, but cannot be immediately awakened. In the sleep center, sleep is identified by observation of a combination of behavioral, physiologic, and electroencephalographic (EEG) features. Sleep in people of all ages is classified into two states: rapid eye movement (REM) and non-REM (NREM) sleep. The rhythmic cycling of REM and NREM patterns, including wake, and the NREM stages of N1, N2, and N3, and REM throughout the course of the sleep period is referred to as sleep architecture. A visual graph of sleep architecture, called a hypnogram, provides an overview of the patient’s night of sleep. Figure 11-1 demonstrates the sleep-stage hypnograms of three patients who underwent an in-laboratory polysomnogram. There are physiologic variables and EEG parameters specific to a certain state of sleep and wakefulness. Sleep stages are determined by assessing EEG, electrooculogram and electromyogram activities, and patient observation. The evaluation of these parameters will be discussed in detail in Chapter 38. Sleep is essential for the maintenance of brain and bodily functions in all age groups.

Sleep behaviors demonstrate great variability between individuals, cultures, societies, and geographical regions (3). They are affected by external factors such as parental beliefs, cultural traditions, socioeconomic status, work and school schedules, use of media, and education about sleep hygiene. Nevertheless, extensive sleep research makes it possible to understand and predict
sleep-wake patterns in different periods of the life cycle (3). The most noticeable age-related developments in sleep and sleep-wake rhythms take place around birth and during the first year of life. They include consolidation of sleep, reductions in the number and duration of naps, and changes in EEG. In the span of infancy through young childhood, sleep is considered particularly essential to development. By age 2, a child has spent about half of his or her life sleeping (2). Significant changes in sleep occur throughout the life span. See Figure 11-2 for the National Sleep Foundation’s (NSF) recommended sleep duration requirements (4).

Figure 11-1 Three sleep-stage hypnograms.

Figure 11-2 Recommended sleep durations.

DEVELOPMENT OF SLEEP-WAKE PATTERNS IN INFANTS AND CHILDREN

Newborns: 0 to 3 Months

Full-term infants are those who are born between 39 and less than 41 weeks of gestation (5). The American Academy of Sleep Medicine (AASM) classifies infants as premature if less than 37 weeks’ gestation, full-term if 37 to 42 weeks, and postterm if born after 42 weeks’ gestation (6). Sleep technologists need to know and document three “ages” of their newborn patients: gestational,
conceptional, and chronologic. The term “gestational age” (GA) refers to the time from the first day of the mother’s last menstrual period to the day of delivery, expressed in weeks. The conceptional age (CA) is the GA plus the number of weeks since birth. The baby’s chronologic age is simply the number of weeks since birth. It is necessary to know the CA of newborns and infants in the sleep center in order to accurately interpret the EEG. EEG characteristics of sleep differ based on conceptional, not chronologic age. A baby born 6 weeks ago is considered 6 weeks of chronologic age, but if born 9 weeks before term will have a CA of 37 weeks. That infant’s sleep patterns would appear similar to those of a newborn who was born at 37 weeks’ gestation. For sleep-stage scoring purposes, the AASM identifies a patient from full-term birth to 2 months’ chronologic age as newborn. For sleep study scoring purposes, the AASM uses the term neonate for a baby’s first 28 days after birth, and infant at age 1 month to 1 year (6).

Full-term newborns sleep approximately 14 to 17 hours per day. Unfortunately for new parents, that sleep occurs in short bouts distributed throughout the day and night, regardless of light or other environmental cues. Bottle-fed babies tend to sleep for approximately 2 to 5 hours at a time versus breastfed babies who sleep in 1- to 3-hour periods (7). Within the sleep period, sleep cycles occur in which the sleep state alternates between REM and NREM, lasting approximately 50 minutes. Interspersed are periods of wakefulness lasting between less than 1 and 2 hours. Sleep-wake cycles depend not so much on circadian rhythm, which is not fully developed at birth, but on hunger and satiety (7) and comfort. An observer can recognize sleep visually, as the eyes remain closed, with noticeable squirming, sucking motions, and small body movements and twitches upon falling asleep. Newborns enter sleep through REM. At this age, approximately half the baby’s sleep is REM, and the other half is NREM. Preterm infants have a higher percentage, as much as 80%, of REM sleep. Undisturbed sleep periods are vital to newborn development, and special care should be taken to preserve the natural sleep periods of the newborn. Particular attention should be paid to preterm babies in the neonatal intensive care area. These patients should have as few disruptions to their REM sleep as possible. Studies have shown that undisturbed sleep periods, when compared to unnaturally disturbed sleep periods, improve cognition in later development (8). There is wisdom in the old saying “never wake a sleeping baby,” particularly in the first few months of life.

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