Quiet sleep

All is quiet. Sleep hovers over me. I am wearied unto death with all that mortals must know weary with fear, weary with grief, weary with talking and planning and fighting, and weary with the old wound in my thigh, and the new wound in my heart—that I have destroyed Ned. 

Non-REM sleep—Sometimes called quiet sleep, it occurs in four stages of gradually deepening rest. 

Quiet sleep, used to describe a sleep state without phasic movements in the first 2 weeks of life, is behaviorally and polysomnographically identical to NREM sleep (4). The actually scored NREM sleep, however, includes the part of half-activated sleep, which comprises a small portion of total NREM sleep (4,8). This type of sleep is found to be almost nonexistent in the first week and increases to about 15% in the second week. By PN 12, NREM sleep is identified by high-amplitude EEG, and increases, rapidly paralleling the increase of wakefulness. Newborn rats do not open their eyes until PN 14. Their wake state is identified as behavioral waking, such as walking and eating without eyes open. This state is only 10-30% in the first 2 weeks of life. Similar to REM sleep development, all states develop to a near-adult level at the end of the fourth week (4). 

Phasic muscle twitches are one of the major REM phasic activities in neonates and also comprise prominent neonatal behavior. A similar feature is found not only in rats but also in other rodents and humans. The period that shows frequent muscle twitches is the first 4 weeks in the rat (4), the first 40 days in the kitten (8), and the first 8 months in the human newborn (13). In humans, this feature is more typical in the premature fetus (14). This activity appears primarily during REM sleep but also in a small portion of NREM sleep, i.e., half-activated sleep (4). The rate of muscle twitches is only 1.5/min and 0.3/min during quiet sleep compared to the rate of 7.5/min and 3/min, respectively, during REM sleep at the same age in PN 10 and PN 20 kittens (8). The number of phasic events dramatically decreases as animals mature (8,9,13,15). It is of interest to note that the dramatic reduction of phasic activities in REM sleep is associated with the increase of wakefulness. 

The decrease of REM sleep without a corresponding increase of wakefulness might be one of the most important features in the short-term effects of neonatal RSD. This fact indicates the immature wake generator or a low waking capacity in the neonatal period. A similar observation was first reported by Mirmiran et al. (61) and described as an increase of NREM (quiet) sleep during neonatal RSD by CLI, without emphasizing its importance. 

Available time to sleep for infants, children, and adults is influenced by a range of environmental and societal factors. In infancy, caretaking practices affect sleep infants sleeping with their mothers have more arousals and less quiet sleep (70), and breast-fed infants wake up more often during the night to nurse (71). Additionally, a small number of researchers have reported that socioeconomic status and other family factors may have an impact on children s sleeping patterns. For example, Sadeh and colleagues (72) assessed the sleep patterns, disruptions, and sleepiness in 140 7-13-year-olds from two-parent,... 

Denenberg et al. (ref. 127) showed that the development of behavioral states in newborn rabbits was markedly changed for at least 40 days after one single theophylline injection on the first day of life. REM sleep vas suppressed, the development of quiet sleep vas delayed, and the level of wakefulness vas increased. The development of behavioral states in rabbits... 

Hilakivi (ref. 128) found that in rats prenatal alcohol exposure during the entire period of pregnancy resulted in less active sleep, more wake and a more frequent interruption of the quiet sleep state by waking episodes on neonatal age. Human newborns with FAS may show abnormal EEG profiles and sleep disturbances such as reduced REM sleep (ref. 25). 

M. Mirmiran and H.A. Corner, Neuronal discharge patterns in the occipital cortex of developing rats during active and quiet sleep, Develop. Brain Res., 3 (1982) 37-48. 

Quiet sleep (includes active-quiet transition preceding quiet sleep)... 

As reviewed by Thoman (1), there is a normal progression in sleep patterns as the infant matures. Quiet sleep and wakefulness become more predominant, whereas active sleep and transitional periods decrease. 

Sleep Assessments. For our studies using the MMS procedure, described above, we measured the percentage of time the infants spent in the crib for the five states Quiet Sleep, Active Sleep, Active-Quiet Transition, Sleep-Wake Transition, and Wake. Examples of the signals recorded for each of these states are presented in Figure 1. In addition to the major sleep states and wakefulness, five other measures of sleep characteristics of the infants were also measured. These measures, listed as follows, were also assessed in our previous studies and found to show measurement reliability (i) Arousals in Quiet Sleep (Ar/QS) Number of brief arousals (>20 s in a 30-s period) occurring within QS, measured as frequency per hour of QS. (ii) Arousals in Active... 

Sleep (Ar/AS) Number of brief arousals (>20 s in a 30-s period) occurring within AS, measured as frequency per hour of AS. (iii) Mean Bout Length of Active Sleep (ASBL) Mean duration in minutes of all bouts of AS in a recording, (iv) Mean Bout Length of Quiet Sleep (QSBL) Mean dura-... 

Fig. 2. Association of maternal plasma (PL) docosahexaenoic acid (DHA) with infant sleep parameters. (A) Maternal DHA vs. infant active sleep (AS) on postnatal day (PND) 2. (B) Maternal DHA vs. infant active sleep to quiet sleep ratio (AS/QS) on PND 2. (C) Maternal DHA vs. infant wakefulness (W) on PND 2. (D) Maternal DHA vs. infant sleep-wake transitional sleep (T) on PND 2. (Reprinted with permission from Ref. 2).

We first analyzed the data to investigate differences in the overall sleep organization of infants of women with (GDM) and without GDM (Control). This was done by comparing the sleep and wake profiles of the two groups. The profiles are made up of the five sleep states that compose the temporal distribution of the infant s sleep and wake states quiet sleep, active sleep, active-quiet transition, sleep-waking transition and waking (these states make up the total sleep-wake time in the crib). 

Postnatal Day 1. The profile analysis indicated a significant difference in the sleep patterns of the two groups on PND 1 (interaction F = 6.024, df 4/120, P < 0.01). The Control group showed more quiet sleep and wakefulness, and less active sleep, with more active-quiet transition sleep. 

In two different studies and populations, the assessment of infant sleep and waking states using the MMS demonstrated consistency for the association between sleep-wake states and DHA status. That is, generally speaking, infants with lower amounts of DHA demonstrated more active sleep and transitional sleep, less quiet sleep and wakefulness, and higher active sleep/quiet sleep ratio, characteristic of a less mature CNS. We conclude that the MMS is a reliable instrument for studying CNS maturity of an individual infant in relation to DHA status. 

Carroll, D.A., Denenberg, V.H., and Thoman, E.B. (1999) A Comparative Study of Quiet Sleep, Active Sleep and Waking on the First Two Days of Life, Dev. Psychobiol. 35,43-48. 

In adult humans and animals, chronic intermittent hypoxia has a facilatory effect manifest by enhanced responses to acute hypoxia (52,53), which appears to involve a serotonin-dependent mechanism (53). Both facilatory and inhibitory effects have been observed in neonatal animals (48,50,51). In addition, state of arousal has been shown to be a factor in the response to repetitive hypoxia in the neonate. In newborn lambs, for example, repetitive hypoxia rapidly became ineffective as a stimulus during active sleep but retained its responses during quiet sleep (49). 

Johnston RV Grant DA, Wilkinson MH, Walker AM. Repetitive hypoxia rapidly depresses cardio-respiratory responses during active sleep but not quiet sleep in the newborn lamb. J Physiol (Lond) 1999 519 571-579. 

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