Continuing Education Activity

Insufficient sleep occurs due to an inadequate opportunity for sleep and is defined as a shorter sleep duration than required to maintain daytime wakefulness. It is prevalent in the US population, with up to one-third of the population reporting poor sleep. It has been associated with cardiovascular disease, obesity, and reduced daytime performance. A thorough clinical evaluation helps diagnose insufficient sleep. Management involves extending total sleep time to a duration expected for age. This activity reviews the assessment and treatment of insufficient sleep and highlights the role of the interprofessional team in evaluating and treating patients with this condition.

Objectives:

• Describe the epidemiology of insufficient sleep.
• Review the pathophysiology resulting from insufficient sleep.
• Outline the typical presentation of a patient with insufficient sleep.
• Explain the management considerations for patients with insufficient sleep.

Introduction

Insufficient sleep is defined as a shorter duration of sleep than required to maintain daytime wakefulness. The American Academy of Sleep Medicine (AASM) and the Sleep Research Society consensus recommends a minimum of 9 hours for children 6 to 12 years of age, 8 hours for adolescents, and at least 7 hours for adults.[1] 

A sleep duration shorter than recommended for age is classified as insufficient sleep duration.[2][1] This article will discuss the etiology, epidemiology, clinical manifestation, evaluation, and prognosis/complications for sleep insufficiency.

Etiology

Insufficient sleep is due to an inadequate opportunity for sleep manifested by a reduced time in bed (number of hours) and/or poor sleep quality (depth of sleep or having sufficient restorative deep stages of sleep). Reduced sleep subsequently affects daytime wakefulness, performance, quality of life, accidents, hypertension, and cardiovascular morbidities.[3][4] 

The current ICSD-3 definition of insufficient sleep syndrome requires the sleep pattern to be present for at least three months.[5]

Epidemiology

Insufficient sleep is a prevalent condition, with up to a third of the U.S. adult population reporting less than 7 hours of sleep per night.[2] According to the National Health and Nutrition Examination Survey (NHANES) conducted between 2005 and 2008, one-third of adults reported sleeping less than 7 hours per night regularly.

Short sleep duration of fewer than 7 hours was reported to affect 37% of adults aged between 20 to 39 years, 40.3% of adults aged between 40 to 59 years, and 32% of adults 60 years or older in this survey. Differences among races were also noted, with 53% of non-Hispanic blacks, 34.5% of non-Hispanic whites, 35.2% of Mexican Americans, and 41.7% of other ethnicities reporting regular short sleep durations. There were no significant differences in prevalence between men (39.8%) and women (35.8%).[6] 

Other studies have reported similar findings of more than one-third of the surveyed population reporting a typical sleep duration of fewer than 7 hours.[7] A Centers for Disease Control and Prevention (CDC) study showed that between 1985 and 2012, the percentage of adults sleeping six or fewer hours a night increased by 31%.[8] 

The National Health Interview Survey assessed different occupational groups for the prevalence of short sleep duration, defined as a self-reported sleep duration of 6 or fewer hours a day. According to the survey, in the transportation/warehouse industry category, production, installation, maintenance, and repair jobs had the highest prevalence of short sleep duration. In contrast, the manufacturing category's installation, maintenance, and repair jobs showed the highest prevalence of short sleep duration.[9]

Pathophysiology

Two physiological processes regulate the sleep-wake cycle. A homeostatic process, also called process S, builds a homeostatic pressure to sleep with the amount of time spent awake and diminishes that pressure with the amount of time spent in sleep. The second process is a biological circadian rhythm, also known as process C, and involves the suprachiasmatic nuclei in the hypothalamus. Process C responds to temporal cues such as sunlight, also known as zeitgebers, which synchronize the internal circadian rhythm with external time.[10][11][12] A restriction in sleep results in a sleep debt manifested as daytime sleepiness. 

Studies on sleep deprivation demonstrate an impact on neurocognition, such as mood, executive function, and cognitive performance. Experiments on chronic partial sleep deprivation, in particular, show that these neurocognitive impairments accumulate over time. Similar neurocognitive deficits occur when sleep deprivation is associated with sleep fragmentation due to an underlying condition.[13] Sleep deprivation has been shown to disrupt hippocampal function, particularly memory consolidation.[14]

While not completely understood, evidence also suggests that sleep deprivation is linked with changes to the epigenome. These alterations involve DNA methylation, histone protein modification, and non-coding RNA.[15] Sleep loss has also increased immune system biomarkers such as interleukin 6 and interleukin 1 receptor antagonists, suggesting a link between sleep and immunity.[16][17]

History and Physical

Patients with insufficient sleep usually complain of sleep deprivation and excessive daytime sleepiness or fatigue, which may affect their daytime functioning. Other symptoms, such as sleep paralysis and hypnogogic hallucinations, may be noted.[18] 

Patients may also report neuropsychological symptoms such as mood changes, irritability, difficulty concentrating, and decreased motivation. A thorough history usually reveals that these patients have a reduced time in bed due to reduced sleep opportunities. In contrast to insomnia, in sleep insufficiency, there is no difficulty in the ability to initiate and maintain sleep naturally. An alarm or a bed partner can disrupt sleep, and in the absence of these disruptions, patients can usually sleep for adequate hours with improvement in daytime symptoms.

Patients may or may not be aware of the discrepancy between the hours of sleep needed and the hours achieved. A good history is essential to formulate an initial provisional diagnosis and to help differentiate it from other causes of disrupted sleep and excessive daytime sleepiness.

Physical examination in patients with insufficient sleep is generally unremarkable and is not explanatory of the patient's presenting complaints. A thorough clinical analysis, nevertheless, must be performed for signs of other sleep disorders.

Evaluation

The International Classification of Sleep Disorders or ICSD-3 criteria requires that several criteria be met to establish a diagnosis of insufficient sleep syndrome.[5] These include:

1. The patient has irrepressible daytime lapses into sleep daily; in prepubertal children, a complaint of behavioral abnormalities due to sleepiness.
2. The patient's total sleep time can be provided through clinical history, sleep diaries, or objective methods such as actigraphy and is usually shorter than expected for age.
3. Sleep pattern is present on most days for a minimum of three months.
4. The patients have decreased total sleep time due to external factors such as an alarm clock or curtailment of sleep by another person and, in the absence of such measures, are generally able to sleep longer.
5. Extending the total sleep time causes the resolution of the symptoms.
6. The symptoms should not be better explained by other untreated sleep disorders, medication or drug effects, or other underlying physical or mental disorders.

The AASM guidelines suggest using actigraphy to evaluate total sleep time in adults suspected of insufficient sleep syndrome. Compared to patient-reported sleep logs, actigraphy provides objective data that may be valuable in assessing poor sleep.[19]

Treatment / Management

Managing insufficient sleep requires extending total sleep time to the amount needed for age. The underlying etiology involves an inadequate opportunity to sleep; hence increasing total sleep time requires lifestyle changes and cognitive and behavioral interventions to allow an adequate opportunity to sleep. These interventions help promote sleep quality and duration in patients reporting poor sleep without a diagnosed sleep disorder.[20] Exercise, relaxation training, stimulus control, and sleep hygiene are the individual components of behavioral interventions. 

Sleep hygiene education involves avoiding caffeine, nicotine, or alcohol close to bedtime, regular bedtimes, and waketimes, and avoiding daytime naps.[21] Irregular sleep timing is associated with daytime sleepiness, and regular sleep timing increases the synchrony between the underlying homeostatic mechanisms regulating sleep and subsequently increases sleep health. Daytime naps can disrupt the homeostatic sleep drive, and naps longer than 30 minutes are not recommended.[22] Caffeine is a stimulant that blocks adenosine receptors in the basal forebrain and hypothalamus and can disrupt sleep if taken up to 6 hours before bedtime.[23][24] 

Similarly, nicotine stimulates cholinergic neurons in the basal forebrain promoting wakefulness and is associated with sleep disruption and a reduced total sleep time.[23][25] Alcohol use before bedtime results in an increased stage N1 and REM rebound sleep along with frequent arousals and has been consistently shown to disrupt consolidated sleep. Its use before bedtime is discouraged in sleep hygiene education.[22]

Regular exercise is recommended as a part of sleep hygiene education and has increased total sleep time and slow-wave sleep.[26] Relaxation and mindfulness exercises are recommended and have improved sleep quality.[27] These components of sleep hygiene principles may help enhance the quality of sleep in individuals with insufficient sleep syndrome.

Differential Diagnosis

Establishing a diagnosis of insufficient sleep syndrome requires ruling out other disorders which can result in curtailed sleep and/or symptoms of daytime sleepiness. The differentials include:

• Sleep-related breathing disorders such as obstructive sleep apnea, central sleep apnea syndromes, and sleep-related hypoventilation disorders
• Central disorders of hypersomnolence such as narcolepsy, idiopathic hypersomnia, or hypersomnia due to a medical condition, medication or substance use, or psychiatric disorder
• Chronic insomnia disorder
• Circadian rhythm sleep disorders 
• Affective disorder
• Periodic limb movement disorder

Insufficient sleep can also result in abnormal mean sleep latency test (MSLT) findings of short sleep latency and two or more sleep-onset REM periods (SOREMPS). Hence, a thorough clinical assessment, sleep diaries, and polysomnography are vital in establishing an accurate diagnosis.[28]

Prognosis

Chronic sleep deprivation has been associated with comorbidities, including elevated blood pressure, heart disease, and stroke.[29] Insufficient sleep can disrupt metabolism, is associated with altered expression of genes and hormones involved in metabolism, and can predispose to obesity.[30] Sleep restriction at a young age is associated with impulsive behavior, depression symptoms, and poor academic performance.[31] 

Daytime sleepiness resulting from insufficient sleep can increase the risk of motor vehicle accidents.[32] Although sleep loss has been associated with harmful physical and psychological complications, it is a modifiable risk factor and is reversible. 

One study evaluated the effects of three nights of recovery sleep after six nights of sleep restriction and found that inflammatory biomarkers such as IL-6 levels, cortisol levels, subjective and objective sleepiness, and fatigue levels returned to baseline after sleep recovery. However, daytime performance measures by psychomotor vigilance testing declined significantly after sleep restriction and were not shown to improve after sleep recovery.[33] 

Long-term studies assessing the effects of sleep extension on variables such as cardiovascular disease and obesity will provide further insight into the outcomes of untreated sleep deprivation.

Complications

Inadequate sleep can have physical and psychological effects that may impact daytime functioning and contribute to comorbidities. The Sleep Heart Health Study reported that insomnia or poor sleep, as evidenced by less than 6 hours of sleep on polysomnography, is associated with an increased risk of cardiovascular disease. Short sleep duration has been associated with a 29 percent higher cardiovascular disease.[34] 

A meta-analysis showed that short and long sleep duration is associated with an increased risk of all-cause mortality, cardiovascular disease, coronary heart disease, and stroke, with the lowest risk noted at around 7 hours of sleep. A 1-hour reduction in sleep compared to 7 hours per day was associated with a 6% increase in all-cause mortality.[35]

Fragmented sleep, measured by an increased arousal index, sleep efficiency, and wake after sleep onset (WASO), has been associated with obesity risk.[36] Sleep restriction has been associated with reduced glucose tolerance, increased cortisol levels, increased ghrelin levels, decreased leptin levels, and increased appetite.[37] Evidence points to an association between the duration and architecture of sleep in children and adolescents with type II diabetes mellitus markers.[38] 

Increased food intake is an adaptive mechanism to maintain the energy needs for additional wakefulness, and sleep recovery can result in a reduced energy intake [39]; these mechanisms may provide a further understanding of the link between insufficient sleep and metabolism. 

Insufficient sleep is associated with poor academic performance.[31] Sleep restriction may also increase impulsive behavior and is related to affective disorders such as depression.[40][41][42] School-aged children with insufficient sleep were observed to have poorer neurobehavioral function, specifically executive and social-emotional function.[43] 

Chronic insufficient sleep may also impair neurobehavioral reaction time and increases attention lapses.[44] Sleep restriction can also result in microsleep periods, with evidence of an increase in cumulative microsleep periods with sleep restriction to 4 hours per night for one week.[45] There is emerging evidence that some higher-level cognitive functions remain affected despite an improvement in alertness with countermeasures, which suggests that sleep deprivation may impact specific cognitive systems in addition to a global decline in cognition.[46] 

Sleep deprivation may result in a higher risk of impulsive behavior and may subsequently increase the risk of unplanned suicide.[47] Improving sleep has shown a significant effect on mental health, depression, and anxiety symptoms, with a dose-response relationship between sleep quality and mental health improvement.[48]

As evidenced by night shift workers, drowsiness resulting from insufficient sleep is a risk factor for motor vehicle accidents.[32] Sleepiness resulting from inadequate sleep contributes to many road traffic accidents.[49] A study showed that when compared with 7 hours of sleep per night, very short sleepers with five or fewer hours of sleep per night were 3.6 to 3.8 times more likely to report drowsy driving and short sleepers with six or fewer hours of sleep were 1.9-2.0 times more likely to report drowsy driving.[50]

Daylight saving time utilizes turning clocks forward by one hour in spring and backward by one hour in autumn. More than 1.5 billion people undergo the transitions involved twice each year, reducing sleep duration by 60.14 minutes and a 10% reduced sleep efficiency.[51][52] 

A meta-analysis of 6 studies showed a 4 to 29% higher incidence of acute myocardial infarction in the spring daylight saving shift.[53] An increase in ischemic heart disease in males and females older than 60 years, as well as in road traffic accidents, has been reported in association with daylight saving time.[54][55]  The American Academy of Sleep Medicine (AASM) published a position statement in 2020 supporting a year-round standard time based on current evidence.[56]

Medical trainees are exposed to extended duration work hours. A systemic review by Levine et al. showed evidence that eliminating shift hours exceeding 16 hours improved patient safety and the residents' quality of life.[57] Interns performing extended overnight shifts are shown to have moderate chronic sleep restriction and significantly reduced alertness levels after on-call night shifts.[58] 

Studies have also shown an association between reduced speed and accuracy with simulated laparoscopic surgery performance and taking night calls.[59] These studies suggest that acute and chronic sleep deprivation due to extended work hours can impact daytime alertness. When comparing a 16-hour work limit to flexible duty hours with extended work hours, no significant difference was found in the mortality of medical patients.[60] 

More recent studies also confirm that resident physicians performing extended shifts of 24 to 28 hours slept significantly less compared with a rapid cycling work roster where continuous shift hours were limited to 16 hours. When adjusted for workload, the residents on rapid cycling work rosters had significantly lower rates of attentional failures and reduced risk of serious medical errors compared to extended duration work rosters.[61]

Deterrence and Patient Education

Patients should be counseled on the behavioral and lifestyle factors likely resulting in insufficient sleep. The fundamental physiological processes involved in sleep, including circadian rhythm and the homeostatic build-up of sleep pressure, should be explained to patients during the clinic visit. This information can provide patients insight into the need for adequate quality and duration of sleep. Educational handouts about good sleep habits may be provided in the clinic or electronically. These educational measures may help patients prevent and treat insufficient sleep syndrome. 

Insufficient sleep is common in school-aged children, and counseling at an early age may assist the patients and their families in establishing good sleep habits.

Enhancing Healthcare Team Outcomes

The diagnosis and management of insufficient sleep benefits from a multidisciplinary approach. Primary care clinicians may play an essential role in screening patients with insufficient sleep and providing these patients with adequate resources to follow sleep hygiene principles.

Since insufficient sleep may present symptoms such as fatigue and mood changes, psychiatrists and neurologists are integral to the multidisciplinary approach. They may help in screening and triaging these patients when indicated. Sleep medicine clinicians are pivotal in ensuring other underlying conditions are appropriately ruled out. Psychologists with expertise in behavioral sleep can educate these patients on the importance of adequate sleep and hygiene principles.

AN interprofessional healthcare team can also enhance the management of sleep insufficiency. Nursing can provide patient counsel, assist in performing exams, take an accurate patient history, and coordinate activities between various clinical participants. Pharmacists can provide valuable counsel if pharmaceutical agents may be affecting the patient's condition. All members of the interprofessional/multidisciplinary team must document their patient interventions and interactions in the patient's medical record so that all team members operate from the same accurate, up-to-date information base.