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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_4704_Библиотеки_им_академика_М_И_Перельмана
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employees along with interaction within the therapeutic team regarding the sleep-
disturbing factors in the ICU setting and techniques for preventing it can signifi-
cantly improve the quality of sleep of the patients. Here, in this chapter, we have
highlighted the factors causing sleep disturbances, their physiological effects on
different systems of the body and a few possible methods to mitigate these
disturbances.
232 P. P. Vaishnav et al.
Keywords Sleep disturbance · Hospitalized patients
· Intensive care unit (ICU) ·
Sleep structure · Sleep deprivation
15.1 Introduction
Sleep is a fundamental physiological process that plays critical roles in various
aspects of well-being and functioning. It serves as a crucial mechanism for recovery,
conserving energy, and ensuring survival. Furthermore, sleep is closely linked to
essential functions including neural development, cognitive processes like learning
and memory, emotional regulation, cardiovascular and metabolic health, and the
clearance of cellular toxins (Mukherjee et al. 2015).
In an intensive care unit setting, patients are artificially put to sleep by medica-
tions. What makes physiological sleep different from similar conditions, such as a
coma, hibernation, or anesthesia, is the fast return to wakefulness a fter a strong
stimulus (Lewandowska et al.
2020). Physiological sleep and stable sleep/wake
cycles are linked to better physical and mental health throughout life. Sleep distur-
bance is defined as the insufficient quantity or quality of sleep with subsequent
daytime impairment and significantly reduced general overall well-being
(Lewandowska et al. 2020).
15.2 Physiological Sleep and Circadian Rhythm
The average duration of nocturnal rest recommended for a healthy adult is around
7–8 h. The biological requirement for sleep is, however, hard to estimate. It varies
individually and depends on genetic factors, age, and gender. Entire nocturnal sleep
can be divided into cycles. Each cycle lasts for 90–110 min (Medrzycka-Dabrowska
et al. 2018). Sleep structure is defined by criteria developed by the American
Academy of Sleep Medicine. Figure 15.1
briefly describes the architecture of the
normal sleep cycle. Each night cycle consists of two phases, namely REM (rapid eye
movement) and NREM (non-rapid eye movement). The REM phase is characterized
by rapid eyeball movement, muscle atonia, and dreams. The NREM phase is divided
into three additional stages: N1—the lightest sleep, the transition from wakefulness
to sleep; N2—the moment of falling asleep, characterized by light sleep; N3—deep
sleep, the hardest to interrupt (Lewandowska et al.
2020). An additional factor,
which normalizes nocturnal rest, is the circadian rhythm. This is mainly influenced
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by light, which indicates the time for rest. Light stimuli that fall on the retina
influence the functioning of the anterior subthalamus, i.e., suprachiasmatic nuclei.
This structure is responsible for synchronizing all circadian systems of the body
(Medrzycka-Dabrowska et al. 2018).
15 Sleep Disturbances in Hospitalized and Intensive Care Unit Patients 233
a sleep cycle
(~90-120 mins)
stage N3 (slow-
wave sleep,
predominant in the
first-half of sleep)
wake after sleep onset
Normal sleep architecture
REM sleep
(predominant in
the second-half of
sleep)
sleep onset
Sleep stage
awake
REM
N1
N2
N3
12 3 4
Sleep duration (hours)
56
7
8
Fig. 15.1 Normal Sleep architecture (Tan et al. 2019)
15.3 Sleep in ICU
The intensive care unit (ICU) is widely regarded as one of the most critical and
crucial healthcare settings. In here medical staff save lives by treating the most
severely ill patients. It is a complex atmosphere and is based on continuous obser-
vation, monitoring, and intervention involved in patient care. Given the overall
workload of ICU medical staff, the physical and technical aspects of care become
the priority, overshadowing the psychological aspects of care and the needs of the
patient. Patients in an ICU are exposed to multiple stimuli including continuous
noise made by the monitoring devices, light emitted by various devices, and frequent
medical interventions. Especially during the nighttime, these disturbances can inter-
rupt and alter patients’ sleep and have a negative impact. Due to the certain
specificities of this unit, medical personnel is not able to eliminate the factors
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responsible for poor sleep quality and lack of physiological rest (Lewandowska et al.
2020).
234 P. P. Vaishnav et al.
Impaired fasting glucose
ventilatory response to hypercapnia
hypoxemia
inspiratory muscle endurance
upper airway collapsibility
neutrophils, particularly immature
cognitive function
mood, unless depressed baseline mood
Equipoise on relationship between sleep
deprivation and delirium
Hyperalgesia
blood pressure
blood pressure variability
cardiovascular
morbidity
&
Temperature dysregulation
(predominantly ↓ body temperature)
Metabolic & Endocrine
Neuropsychological
Cardiovascular
Pulmonary
Immune
↓
↓
↓
↓
↓
↓
↓
↓
↓
↓
populations
persistent low-level inflammation
Equivocal data on cytokine expression
Long-term:
Long-term:
response to vaccination,
Fig. 15.2 Effects of Sleep disruption on organ systems (Chang et al. 2020)
Although patients may achiev
e an acceptable amount of sleep during 24 h while
receiving care in the ICU, it is noted that this sleep is usually fragmented and has a
significantly abnormal architecture. Patients have an increased amount or percentage
of stage 1 sleep which typically suggests sleep fragmentation due to a sleep disorder
(Pulak and Jensen 2016).
An increased number of awakenings may have similar consequences and adverse
health effects as sleep deprivation. These include weakening of the immunological
system leading to an increased risk of infections, reduced respiratory parameters,
increased perception of pain, reduced glucose tolerance, increased sympathetic
activity, impaired wound healing, and increased protein catabolism. The above-
mentioned factors were identified during studies performed on healthy people. In a
hospital or an ICU setting sleep disturbances in patients therefore can lead to more
pronounced consequences of sleep deprivation, which in turn can hamper the
recovery process (Medrzycka-Dabrowska et al. 2018). Sleep deprivation impairs
cognition, ranging from apathy and confusion to delirium, all of which may lead to
increased morbidity and mortality (Lewandowska et al. 2020).
Below is a brief description of how sleep disturbance in any hospitalized or ICU
patient can affect different vital organ systems (Fig.
15.2):
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15 Sleep Disturbances in Hospitalized and Intensive Care Unit Patients 235
15.4 Neurophysiological Effects
Drouot et al. combined EEG spectral analysis and visual quantitative EEG analysis
during sleep and wakefulness and identified subclinical alterations in sleep/wake
states, which may affect one-third of conscious non-sedated ICU patients with
respiratory failure (Drouot et al.
2012). These abnormalities may reflect a subclinical
form of brain dysfunction that may be associated with an increased risk of delirium
(Pulak and Jensen
2016).
An association between delirium and sleep disturbance in the ICU is suggested,
although medications used to control delirium may be contributing to deleterious
effects on sleep and overall psychiatric outcomes (Pulak and Jensen
2016).
Studies with sleep-promoting interventions have been shown to reduce the
number and duration of delirium episodes among general medical wards, medical
ICU, and surgical ICU patients (Chang et al. 2020).
Other studies revealed that during their stay in a hospital or an ICU, patients could
remember frequent interruptions, pain, anxiety, and fear, which all reduced their
ability to sleep (Medrzycka-Dabrowska et al.
2018). One study, which included
464 patients, demonstrated that 51% of them experienced dreams and nightmares,
whereas 14% of these subjects reported nightmares negatively influencing their
quality of life even 6 months after their ICU stay (Granja et al. 2005).
15.5 Cardiovascular System
Elevated blood pressure is a well-known consequence of short-term sleep depriva-
tion (Chang et al. 2020). The hypertensive effect of sleep deprivation has been
attributed to an increase in sympathetic activity (Zhong et al. 2005), a reduction in
maximum endothelium-dependent vasodilation, and an upward resetting of the
baroreflex set point (Chang et al. 2020). In addition to its hypertensive effect ,
sleep deprivation is also correlated with increased blood pressure variability
(Zhong et al.
2005).
The concentrations of C-reactive protein (CRP) , a marker of inflammation that
has been shown to have predictive value on future myocardial infarction and stroke
in apparently healthy individuals, are higher after experimental sleep deprivation
(Chang et al. 2020).
15.6 Respiratory System
Most studies have found a reduced ventilatory response to hypercapnia and hypox-
emia after 24 h of sleep deprivation (Chang et al. 2020), although this find ing has
been disputed by a newer study performed with stricter control of subject behavior
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and environment (Spengler and Shea 2000). Short-term sleep deprivation has also
been shown to lessen inspiratory muscle endurance (Chang et al. 2020).
236 P. P. Vaishnav et al.
Experimental sleep deprivation has also been found to increase upper airway
collapsibility, which can cause
or contribute to preexistin g obstructive sleep apnea
(OSA) and lead to challenges in successful extubation (Chang et al.
2020).
Studies on patients with OSA have also demonstrated that cerebral blood flow
(CBF) decreases during episodes of apneas, and intracranial pressure increases in
linear proportion to the length of an apneic event. The impact of sleep deprivation on
pulmonary funct ion is relevant in the Neuro ICU given the proportion of patients
who require ventilatory support and the prevalence of sleep-disordered breathing
among stroke and transient ischemic attack patients (Chang et al.
2020).
The reduction of CBF in OSA may be attributed to damage to brain areas
essential for vascular regulation (including the insular, cingulate, and medial frontal
cortices; raphe and ventrolateral medulla) and an unexplained blunting of the typical
vasodilator response to increased PaCO2 (Yadav et al.
2013). Such results highlight
the possible complications of sleep deprivation for Neuro ICU patients with ische-
mic brain injury but may not be generalizable (Chang et al.
2020).
15.7 Effects of Sleep Deprivation on Immune Function
Sleep plays a vital role in promoting adaptive immune responses, which ultimately
contribute to the development and enhancement of the immune system’s ability to
recognize and respond to pathogens and other threats. This impact is rooted in the
reciprocal interaction between the central nervous system (CNS) and the immune
system, along with the direct neural connections between the autonomic nervous
system and the immune system.
Below are some different ways in how sleep deprivation can potentially affect
healing, both in terms of tissue repair and cellular immune function (Pulak and
Jensen
2016).
• Interleukin 1 (IL-1) and tumor necrosis factor have been shown to regulate
NREM sleep; therefore, loss of sleep may result in impairm ent of host defenses
against infection.
• Signi ficant reduction in the number and phagocytic activity of lymphocytes was
found to be decreased by 13% as compared with non-sleep deprived individuals.
• Benedict et al. (Beauchemin and Hays 1998) found that Interleukin-7 levels were
increased during normal sleep.
• IL-7 facilitates the transition of CD8þ effector to memory T-cells and lengthens
the survival of the T-cell memory cells.
• Natural killer T-cell activity was found to be negatively correlated with the
severity of insomnia.
• Sleep restriction can also result in reduced antioxidant activity (catalase and
glutathione), decreased spleen weight, alterations in leukocyte and lymphocyte
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counts, and the production of serum antibodies without the presence of an
antigen.
15 Sleep Disturbances in Hospitalized and Intensive Care Unit Patients 237
15.8 Hormonal System and Metabolism
Lack of sleep leads to significant alterations in homeostatic mechanisms and has a
profound impact on neuroendocrine stress systems. Wakefulness enhances catabo-
lism, while sleep shifts metabolism in favor of anabolism. Urinary nitrogen secretion
increases markedly with sleep reversal (change in diurnal activity) and sleep depri-
vation (Pulak and Jensen
2016).
Spiegel et al. (Caldwell et al. 2002) found that sleep-deprived patients showed
glucose intolerance, insulin resistance, lower thyrotropin, and elevated evening
cortisol levels (Spiegel et al.
1999). Sleep-deprived patients are found to have higher
oxygen consumption, carbon dioxide production, and catecholamine levels, likely as
a stress response (Pulak and Jensen
2016).
15.9 Factors Affecting Sleep
Many factors disturb the sleep of patients in an ICU setting with specific environ-
ments and invasive therapeutic interventions. The inability to obtain physiological
sleep depends on the patient’s illness, varying severity of the illness, and previous
sleep experience. Below we describe the factors affecting sleep in an ICU environ-
ment under the classification of environmental factors, patient care activities includ-
ing pharmacological interventions, mechanical interventions, and patient-related
factors.
15.9.1 Environmental Factors
ICU could be a place of anxiety, fear, and apprehension for any patient. Patients
rarely have time to prepare for acute change mentally and physically in such a fast-
paced critical environment. These factors are further exacerbated by sedative med-
ications, the inability to communicate or move, leading to a state of low morale and
sleep disturbance. ICU patients require frequent monitoring and repeated interven-
tions for diagnostic tests, vital signs, blood collection, and medication administra-
tion. This leads to a constant awakening, heightened noise, and disturbing light
levels in an ICU setting, thus all contributing to disrupted sleep (Pulak and Jensen
2016).
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238 P. P. Vaishnav et al.
15.9.1.1 Noise
The World Health Organization’s (WHO) external review policy on community
noise has produced guidelines that identify specific noise levels within hospital
environments. The recommendations include noise levels not exceeding 35 dB
(A) during the night and 40 dB(A) during the day. In general, this is far exceeded
by the average noise levels in an ICU. Recent studies show the average noise level in
ICU to be 55–66 dB(A) with peaks reaching as high as 85 dB(A). These noise levels
are considered enough to stimulate cardiovascular and endocrine systems disrupting
sleep as a result of noise-induced stress modulation (Pulak and Jensen 2016). [For
reference, the noise levels of an average vacuum cleaner are about 70 db] (Tan et al.
2019).
Furthermore, noise can diminish the magnitude of overnight melatonin release in
healthy humans (Huang et al. 2015). Thus, it could be speculated that noise in the
hospital may lead to the development of sleep disturbances and circadian disruption
in patients. Supporting this hypothesis, two studies on the general medicine and
oncology floors found that 27–43% of patients identified noise as a major cause of
poor sleep (Grossman et al.
2017; Yoder et a l. 2012).
A systematic review by K. Honarmand showed that among ICU-related factors,
patients reported noise as being one of the most disruptive factors for sleep in the
ICU (Honarmand et al. 2020).
A study by S. Bihari et al. concluded that the most disruptive source of ICU noise
is bedside phones and ICU mechanical alarms. However, the study did not support
the hypothesis that ICU noise is the most disruptive stimulus (Bihari et al.
2012).
Freedman et al. used PSG and time-synchronized recording of environmental
noise, directly linked to noise arousals from sleep, and determined that noise was
responsible for only 15% of all arousals and awakenings (Freedman et al.
2001).
Healthy individuals slept relatively well in the potentially disruptive environment
of the ICU and although noise accounted for a significant proportion of sleep
disruption, its extent was not pathologic. High-peak noise may be more disruptive
than general background noise; however, even peaks were not found that problem-
atic. Therefore, the relative contribution of noise and other components of the ICU
environment to the pathogenesis of ICU sleep disruption is largely unknown and
remains a complex issue (Pulak and Jensen 2016).
15.9.1.2 Light
The light–dark cycle is probably the most powerful entraining factor in the human
sleep–wake cycle and ultimately the development of restful surroundings (Pulak and
Jensen
2016). Unnatural light characteristics that are often found in the hospital may
contribute to impaired sleep and circadian disruption. Artificial blue-enriched light
during evening hours delays the production of melatonin and impairs sleep quality
(Tan et al. 2019). Medical inpatients are often subjected to dim light conditions
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during the daytime and bright light during the evening and night hours (Chang et al.
2020). For example, the maximal nocturnal luminance in ICU can reach as high as
1000–3000 lux during the night (Meyer et al. 1994). A potential reason why ICU
patients lack the typical nocturnal peak of melatonin secretion and show a delayed
circadian rhythm (Tan et al.
2019).
15 Sleep Disturbances in Hospitalized and Intensive Care Unit Patients 239
Dunn et al. recorded ICU activ
ity that was occurring or not occurring, while
various light sources were illuminated. The activity associated with the greatest
amount of light exposure was obtaining samples for laboratory tests, while the
second activity most often recorded while the light was on was “none” (Dunn
et al.
2010). This suggested a lack of simple vigilance on the part of healthcare
providers (Pulak and Jensen 2016).
Natural light exposure is often unevenly distributed in different rooms of the
hospital. This may hamper the ability of patients sleeping further from the window to
be in sync with the natural light/dark cycle, with possible undesirable implications of
sleep disturbance (Tan et al.
2019). A study involving 1057 patients from various
medical floors pointed to the role of natural daylight exposure on patients’ length of
stay. Patients located in southwest-facing rooms (mean 220 lux between 8 am and
6 pm) had a 29% shorter average length of stay, compared to patients in the
northwest-facing rooms (mean 101 lux) (Choi et al.
2012). Furthermore, brighter
compared to darker hospital rooms correlated with reduced duration of hospi taliza-
tion and decreased mortality rates. in patients with myocardial infarction (n = 628)
(Beauchemin and Hays
1998). Such studies implicate that circadian disruption due
to weak light exposure may adversely affect patients’ health and recovery (Tan et al.
2019).
15.9.2 Patient Care Activities
The need for clinical interventions increases exponentially in ICU as many different
assessments are scheduled on an hourly basis such as vital sign monitoring, fluid
balance assessments, neurological assessments, and pharmacological administration.
These interventions in combination with basic care needs establish an environment
in which sleep is easily deprioritized and disrupted (Delaney et al. 2015).
In Lee et al.’s study, 50% of patients reported being woken 2–5 times throughout
the night caused difficulties falling back to sleep once woken (Lee et al. 2007). The
frequency of disruptions for mechanically ventilated patients was found to be
substantially higher, with Le et al. reporting that patients experienced 20–60 disrup-
tions per hour (Le et al.
2012).
However, a systematic review by K. Honarmand et al. showed that care inter-
ventions were not associated with sleep disruption in the majority studies
(Honarmand et al.
2020). Approximately 20% of patient care activities resulted in
arousal or awakening, accounting for only 7% of observed sleep disruption. There-
fore, patient care activities, although frequent, may not be a predominant source of
sleep disruption in ICU patients (Pulak and Jensen 2016).
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240 P. P. Vaishnav et al.
15.9.2.1 Pharmacological Intervention
Medications can affect sleep in various ways. They may contribute to disturbed sleep
and adversely affect normal sleep physiology and architecture. Medications may
affect the CNS directly by penetrating the blood–brain barrier or indirectly by
affecting a medical or psychiatric illness that results in altered sleep. Some may
disrupt sleep by their effect on preexisting sleep disorders and others have an equally
disruptive effect when withdrawn abruptly (Pulak and Jensen
2016).
Sedatives
Sedation is a mode in which patients are put into a state of sleep that is not
physiological, not circadian, or fully reversible with external stimuli. The most
common ICU sedatives are those that interact with g-aminobutyric acid (GABA)
receptors in the CNS (Pulak and Jensen
2016). At low doses, benzodiazepines and
propofol suppress slow wave sleep (SWS) and may decrease REM sleep. They
shorten sleep latency, decrease arousal, and increase NREM stage 2 sleep. Higher
doses are associated with a characteristic slowing of the EEG and both can lead to a
burst suppression pattern, thus the EEG shows more of a comatose pattern. With
repeated use, benzodiazepines can completely abolish NREM stage 4 sleep (Pulak
and Jensen 2016).
Dexmedetomidine, a selective alpha 2-adrenoreceptor agonist, is increasingly
utilized in the Neuro ICU due to its analgesic, sedative, and anxiolytic effects
while maintaining patient arousability and minimizing respiratory depression
(Chang et al.
2020). [The use of dexmedetomidine has effects closer to the naturally
occurring sleep pathway in the CNS as it inhibits Norepinephrine release by locus
ceruleus. Dexmedetomidine preserves a natural sleep pattern and induces coopera-
tive sedation] (Pulak and Jensen
2016). While dexmedetomidine is more expensive,
several studies have found it to be more cost-effective than traditional sedatives as it
is associated with reduced ICU stay costs and shorter times to extubation (Chang
et al. 2020).
Analgesics
Opioids form a major part of pain management in critically ill patients. They affect
the natural sleep pattern via the Ponto-thalamic arousal pathway. Even single doses
of opioids potently suppress SWS (Pulak and Jensen
2016). Rapid eye movement
(REM) sleep suppression by opioids is a dose-dependent phenomenon (Pulak and
Jensen 2016). Opioids increase NREM stage 2 sleep and increase wakefulness.
However, if pain is a predominant cause of disturbed sleep, the overall effects of
opioids would likely be to improve sleep (Caldwell et al.
2002).
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15 Sleep Disturbances in Hospitalized and Intensive Care Unit Patients 241
Nonsteroidal anti-inflammatory medications can adversely affect sleep by
decreasing sleep efficiency and increasing awakenings. These effects may be
because of inhibition of prostaglandin synthesis, decreased melatonin secretion,
attenuation in nocturnal body temperature, or gastric irritation (Murphy et al.
1994).
Cardiovascular Medications
Cardiovascular medications are widely used medications in an ICU environment
(Pulak and Jensen
2016). Beta-blockers are known to cause nightmares, insomnia,
and REM sleep suppression. These CNS effects are mainly due to their lipid
solubility allowing them to cross the blood-brain barrier (Pulak and Jensen 2016).
Adrenergic receptor agonists like norepinephrine, epinephrine, and dopamine are
associated with insomnia and suppression of REM sleep and SWS (Bourne and
Mills
2004). Amiodarone, a highly effective antiarrhythmic has also been known to
cause neurological side effects in up to 40% of patients. These include insomnia and
nightmares (Pulak and Jensen
2016). Diuretics disrupt sleep due to increased
frequency of urination or requirement of painful urinary catheters (Chang et al.
2020).
Respiratory Medications
Patients on mechanical ventilation and those who have acute or chronic respiratory
conditions with symptoms are likely to receive inhaled b-adrenergic receptor ago-
nists while in the ICU. Central nervous system stimulation with associated restless-
ness, agitation, and insomnia is a well-known adverse effect. The overall effect on
sleep may be positive, only if these medications alleviate dyspnea and desaturations
(Pulak and Jensen
2016).
Corticosteroids
Corticosteroids are known to cause REM sleep suppression and increased nocturnal
awakenings. Steroid psychosis or hypermania can cause insomnia (Wolkowitz et al.
1990).
15.9.2.2 Mechanical Interventions
Radiological and Laboratory Testing
In any ICU setting patients frequently undergo multiple testing, including blood
draws, chest X-rays, echocardiogram, and sometimes patients need to be transported
out of the unit for investigations including a computed tomography scan (CT scan)
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