Infant sleep is an act of sleeping by an infant or a newborn. It differs significantly from sleep during adulthood. [1] [2] [3] Unlike in adults, sleep early in infancy initially does not follow a circadian rhythm. Infant sleep also appears to have two main modes - active, associated with movement, and quiet, associated with stillness - exhibiting distinct neurological firing patterns. [4] Sleep duration is also shorter. As the infant ages, sleep begins to follow a Circadian rhythm and sleep duration increases. Infants nap frequently. Infants are also particularly vulnerable during sleep; they are prone to suffocation and SIDS. As a result, "safe" sleep techniques have been the subject of several public health campaigns. [5] Infant sleep practices vary widely between cultures and over history; historically infants would sleep on the ground with their parents. In many modern cultures, infants sleep in a variety of types of infant beds or share a bed with parents. Infant sleep disturbance is common, [6] and even normal infant sleep patterns can cause considerable disruption to parents' sleep. [1]
In the first week of life, infants will sleep during both the day and night and will wake to feed. Sleep cycle duration is usually short, from 2–4 hours. [7] Over the first two weeks, infants average 16–18 hours of sleep daily. Circadian rhythm has not yet been established and infants sleep during the night and day equally. [3] In the first month of life, 95% of infants will wake during the night. [2] At around 2 months, a day-night pattern begins to gradually develop. [8] At around 3 months, sleep cycle may increase to 3–6 hours, [2] and the majority of infants will still wake in the night to feed. [9] By 4 months, the average infant sleeps 14 hours a day (including naps), but this amount can vary considerably. [10] By 8 months, most infants continue to wake during the night, though a majority are able to fall back asleep without parental involvement. [2] At 9 months, only a third of infants sleep through the night without waking. [3] Daytime sleeping (naps) generally doesn't cease until 3 to 5 years of age.
Infant sleep in the first year can be categorised into active sleep (AS) and quiet sleep (QS). Active sleep is similar to the adult REM sleep in that it is characterised by eye and other kinds of movement; however, unlike adults in REM, infants tend to enter AS at the beginning of their sleep cycle, as opposed to the end of it like REM in adults. [2] Infants spend about half their time in AS/REM and half in QS, a much higher proportion than adults, who only spend about a quarter of their time in REM. It's hypothesised this difference in sleep pattern is related to the shorter sleep cycles and more frequent waking of infants. By 3 months infants become more likely to enter quiet sleep (or NREM, not-REM) at the beginning of their sleep cycle. After 3 months, infants tend to alternate between AS/QS for 50 minutes duration, as opposed to the longer cycle in adult sleep (90 minutes). Sleep cycle duration starts to resemble adult sleep more at 6 months, but doesn't fully resemble adult sleep until around 3 years old, which is generally around the time napping ceases as well. [2]
Frequent night waking and the short sleep cycle in infants is thought to be adaptive. Because infants have small stomachs and are undergoing rapid growth, they need to eat very frequently in order to get enough nutrition. Frequent night awakenings are also protective against SIDS. [11]
Sleep is a state of reduced mental and physical activity in which consciousness is altered and certain sensory activity is inhibited. During sleep, there is a marked decrease in muscle activity and interactions with the surrounding environment. While sleep differs from wakefulness in terms of the ability to react to stimuli, it still involves active brain patterns, making it more reactive than a coma or disorders of consciousness.
An infant or baby is the very young offspring of human beings. Infant is a formal or specialised synonym for the common term baby. The terms may also be used to refer to juveniles of other organisms. A newborn is, in colloquial use, an infant who is only hours, days, or up to one month old. In medical contexts, a newborn or neonate is an infant in the first 28 days after birth; the term applies to premature, full term, and postmature infants.
Rapid eye movement sleep is a unique phase of sleep in mammals and birds, characterized by random rapid movement of the eyes, accompanied by low muscle tone throughout the body, and the propensity of the sleeper to dream vividly.
Delayed sleep phase disorder (DSPD), more often known as delayed sleep phase syndrome and also as delayed sleep–wake phase disorder, is the delaying of a person's circadian rhythm compared to those of societal norms. The disorder affects the timing of biological rhythms including sleep, peak period of alertness, core body temperature, and hormonal cycles.
The sleep cycle is an oscillation between the slow-wave and REM (paradoxical) phases of sleep. It is sometimes called the ultradian sleep cycle, sleep–dream cycle, or REM-NREM cycle, to distinguish it from the circadian alternation between sleep and wakefulness. In humans, this cycle takes 70 to 110 minutes. Within the sleep of adults and infants there are cyclic fluctuations between quiet and active sleep. These fluctuations may persist during wakefulness as rest-activity cycles but are less easily discerned.
Polyphasic sleep is the practice of sleeping during multiple periods over the course of 24 hours, in contrast to monophasic sleep, which is one period of sleep within 24 hours. Biphasicsleep refers to two periods, while polyphasic usually means more than two. Segmented sleep and divided sleep may refer to polyphasic or biphasic sleep, but may also refer to interrupted sleep, where the sleep has one or several shorter periods of wakefulness, as was the norm for night sleep in pre-industrial societies.
Actigraphy is a non-invasive method of monitoring human rest/activity cycles. A small actigraph unit, also called an actimetry sensor, is worn for a week or more to measure gross motor activity. The unit is usually in a wristwatch-like package worn on the wrist. The movements the actigraph unit undergoes are continually recorded and some units also measure light exposure. The data can be later read to a computer and analysed offline; in some brands of sensors the data are transmitted and analysed in real time.
Circadian rhythm sleep disorders (CRSD), also known as circadian rhythm sleep-wake disorders (CRSWD), are a family of sleep disorders which affect the timing of sleep. CRSDs arise from a persistent pattern of sleep/wake disturbances that can be caused either by dysfunction in one's biological clock system, or by misalignment between one's endogenous oscillator and externally imposed cues. As a result of this mismatch, those affected by circadian rhythm sleep disorders have a tendency to fall asleep at unconventional time points in the day. These occurrences often lead to recurring instances of disturbed rest, where individuals affected by the disorder are unable to go to sleep and awaken at "normal" times for work, school, and other social obligations. Delayed sleep phase disorder, advanced sleep phase disorder, non-24-hour sleep–wake disorder and irregular sleep–wake rhythm disorder represents the four main types of CRSD.
Shift work sleep disorder (SWSD) is a circadian rhythm sleep disorder characterized by insomnia, excessive sleepiness, or both affecting people whose work hours overlap with the typical sleep period. Insomnia can be the difficulty to fall asleep or to wake up before the individual has slept enough. About 20% of the working population participates in shift work. SWSD commonly goes undiagnosed, so it's estimated that 10–40% of shift workers have SWSD. The excessive sleepiness appears when the individual has to be productive, awake and alert. Both symptoms are predominant in SWSD. There are numerous shift work schedules, and they may be permanent, intermittent, or rotating; consequently, the manifestations of SWSD are quite variable. Most people with different schedules than the ordinary one might have these symptoms but the difference is that SWSD is continual, long-term, and starts to interfere with the individual's life.
The Safe to Sleep campaign, formerly known as the Back to Sleep campaign, is an initiative backed by the US National Institute of Child Health and Human Development (NICHD) at the US National Institutes of Health to encourage parents to have their infants sleep on their backs to reduce the risk of Sudden Infant Death Syndrome, or SIDS. The target age group of the campaign is 0–1 years of age, because this is when babies are at the greatest risk of experiencing SIDS. Since "Safe to Sleep" was launched in 1994, the incidence of SIDS has declined by more than 50%. However, there has been a rise in infant sleep-related suffocation events. Consequently, the campaign has broadened its goal to focus on safe sleep conditions and further preventative measures.
Sleep in animals refers to a behavioral and physiological state characterized by altered consciousness, reduced responsiveness to external stimuli, and homeostatic regulation observed in various animals. Sleep has been observed in mammals, birds, reptiles, amphibians, and some fish, and, in some form, in insects and even in simpler animals such as nematodes. The internal circadian clock promotes sleep at night for diurnal organisms and in the day for nocturnal organisms. Sleep patterns vary widely among species. It appears to be a requirement for all mammals and most other animals.
Sleep deprivation, also known as sleep insufficiency or sleeplessness, is the condition of not having adequate duration and/or quality of sleep to support decent alertness, performance, and health. It can be either chronic or acute and may vary widely in severity. All known animals sleep or exhibit some form of sleep behavior, and the importance of sleep is self-evident for humans, as nearly a third of a person's life is spent sleeping.
A nap is a short period of sleep, typically taken during daytime hours as an adjunct to the usual nocturnal sleep period. Naps are most often taken as a response to drowsiness during waking hours. A nap is a form of biphasic or polyphasic sleep, where the latter terms also include longer periods of sleep in addition to one period. For years, scientists have been investigating the benefits of napping, including the 30-minute nap as well as sleep durations of 1–2 hours. Performance across a wide range of cognitive processes has been tested.
Sleep training is a set of parental intervention techniques with the end goal of increasing nightly sleep in infants and young children, addressing “sleep concerns”, and decreasing nightime signalling. Although the diagnostic criteria for sleep issues in infants is rare and limited, sleep training is usually approached by parents or caregivers self identifying supposed sleep issues.
The neuroscience of sleep is the study of the neuroscientific and physiological basis of the nature of sleep and its functions. Traditionally, sleep has been studied as part of psychology and medicine. The study of sleep from a neuroscience perspective grew to prominence with advances in technology and the proliferation of neuroscience research from the second half of the twentieth century.
Emotions play a key role in overall mental health, and sleep plays a crucial role in maintaining the optimal homeostasis of emotional functioning. Deficient sleep, both in the form of sleep deprivation and restriction, adversely impacts emotion generation, emotion regulation, and emotional expression.
Sleep deprivation – the condition of not having enough sleep – is a common health issue for students in higher education. This issue has several underlying and negative consequences, but there are a few helpful improvements that students can make to reduce its frequency and severity.
Sleep is known to play an important role in the etiology and maintenance of bipolar disorder. Patients with bipolar disorder often have a less stable and more variable circadian activity. Circadian activity disruption can be apparent even if the person concerned is not currently ill.
Behavioral sleep medicine (BSM) is a field within sleep medicine that encompasses scientific inquiry and clinical treatment of sleep-related disorders, with a focus on the psychological, physiological, behavioral, cognitive, social, and cultural factors that affect sleep, as well as the impact of sleep on those factors. The clinical practice of BSM is an evidence-based behavioral health discipline that uses primarily non-pharmacological treatments. BSM interventions are typically problem-focused and oriented towards specific sleep complaints, but can be integrated with other medical or mental health treatments. The primary techniques used in BSM interventions involve education and systematic changes to the behaviors, thoughts, and environmental factors that initiate and maintain sleep-related difficulties.
Sleep problems in women can manifest at various stages of their life cycle. Both subjective and objective data indicate that women are at an increased risk of experiencing different types of sleeping problems during different life stages. Factors such as hormonal changes, aging, psycho-social aspects, physical and psychological conditions, and the presence of sleeping disorders can disrupt women's sleep. Research supports the presence of disturbed sleep during the menstrual cycle, pregnancy, postpartum period, and menopausal transition. The relationship between sleep and women's psychological well-being suggests that the underlying causes of sleep disturbances are often multi-factorial throughout a woman's lifespan.