Sleep requirements differ among individuals and within different age groups. In recognition of this, in 2015, the National Sleep Foundation (NSF) updated what is considered normal sleep requirements for various age groups (1). The NSF also broke down recommendations for sleep for adults into three categories rather than just one for all adult ages and created new age grouping for younger adults ages 18 to 25, adults ages 26 to 64, and adults ages 65 or older. The scientifically grounded guidelines were developed on the basis of a rigorous, systematic review of scientific literature on sleep duration, health, performance, and safety. The different age categories now have recommended sleep amounts, what may be appropriate, and what is not recommended.

It is no longer sufficient to simply say an adult should get 8 hours of sleep each night. Sleep technologists need to be aware of how much sleep is recommended for each age group. Even with sufficient sleep time, sleep quality is still important to enable best function. The best indicator of sufficient good-quality sleep is waking up feeling refreshed, alert, and performing at a peak level during wake time.

Sleep deprivation in an individual can be caused by insufficient duration of sleep (quantitative sleep deprivation), a fragmented or interrupted sleep period (qualitative sleep deprivation), or a combination of both factors. Sleep deprivation can be either chronic or acute. The subjective assessment of the quality of sleep is based on the amount of sleep, continuity of sleep, and depth of the sleep. See Table 6-1 for the NSF’s sleep duration recommendations (2).

Acute sleep deprivation refers to no sleep or a reduction in the usual total sleep time, usually lasting 1 or 2 days (3). Chronic sleep insufficiency (also called sleep restriction) exists when an individual routinely sleeps less than the amount required for optimal functioning.

The prevalence of sleep deprivation in the industrialized world appears to be on the rise. In February of 2017, the Centers for Disease Control and Prevention’s (CDC) Morbidity and Mortality weekly report estimated that more than a third of Americans were not getting enough sleep on a regular basis. The major consequences of chronic sleep deprivation are fatigue, excessive daytime sleepiness, clumsiness, weight changes, and adversely affected cognitive function. Consequences can also include motor vehicle or industrial accidents, negative socioeconomic and public health outcomes, reduced academic and job performance, and a reduced sense of well-being. According to Johns Hopkins sleep researcher Patrick Finan, sleep deprivation can affect your judgment in such a way that you don’t notice its effects (4). In a world that is increasingly changing into a “global community,” the encroaching demands on the sleep-wake cycle of an individual pose a significant dilemma.

Major industrial disasters, such as those at Chernobyl, Three Mile Island, and Bhopal, and serious accidents, such as those involving the Exxon Valdez and the Space Shuttle Challenger, have been officially attributed to errors in judgment caused at least in part by sleepiness in the workplace (5). One in 25 adults in the United States report falling asleep at the wheel at least once in a month. There are nearly 6,000 fatal car crashes caused by drowsy driving each year. People who are sleep deprived have nearly three times the risk for type 2 diabetes than nonsleep-deprived individuals and have an increased risk for high blood pressure, and a 48% increased chance of developing heart disease. Getting less than 5 hours of sleep nightly puts an individual at a 50% higher risk of obesity as there is an increase in the hunger hormone ghrelin and a decrease in the appetite-control hormone leptin.

The 2014 NSF Health Index revealed that as many as 35% of Americans reported that their sleep quality was “poor” or “only fair” and that Americans slept 40 minutes longer on nonwork days. Nearly 40% indicated that they snored more than a few nights per week, with 17% of respondents being told by their physician that they have a sleep disorder; 24% of women reported they woke up feeling well-rested 0 days out of 4 as against 16% of men. Adding up, nearly 15% of the US workforce works for hours outside of the traditional 9-a.m.-to-5-p.m. workday. Most sleep technologists are part of that workforce. Even if shift workers technically get sufficient sleep during the day, they may still experience some symptoms of shift work disorder.
Approximately 10% of shift workers are believed to be suffering from shift work disorder. Roughly between 25% and 30% of shift workers experience symptoms of excessive sleepiness or insomnia. This is especially problematic when most shift workers, such as those in the medical field or transportation industry, are required to be alert and able to make quick and important decisions (6).

The International Classification of Sleep Disorders, 3rd edition, lists insufficient sleep syndrome (ISS) also known as behaviorally induced ISS, insufficient nocturnal sleep, chronic sleep deprivation, and sleep restriction, under Central Disorders of Hypersomnolence (23). This sleep disorder is extrinsic—it originates from causes outside of the body. Diagnostic criteria consist of daily need to sleep, or lapses into sleep, during the day (for children there is a complaint of behavior abnormalities attributed to sleepiness).

The sleep time, obtained via personal history, sleep logs, or actigraphy, is shorter than expected for the age group. The patient curtails sleep by an alarm clock or wakening by others and generally sleeps longer on weekends and vacations. The curtailing of sleep is present most days for at least 3 months. Extending the total sleep time resolves symptoms of sleepiness. The symptoms are also not better explained by another untreated sleep disorder, medication effects, or a medical, neurologic, or mental disorder. Actigraphy is commonly used with sleep diaries for 2 to 3 weeks to help document the patient’s time in bed, sleep latency, total sleep time, and sleep efficiency. PSG and MSLT are not required to establish this diagnosis. Rather, a therapeutic trial of longer sleep episodes is used and if the longer sleep durations lead to resolution of the symptoms this is sufficient to diagnose ISS.

If PSG is performed, it would reveal reduced sleep latency and a greater-than-90% sleep efficiency, reflecting the need for more sleep. It is also common to see slow-wave sleep (SWS) rebound (23, 24, 25) at the expense of other nonrapid eye movement (NREM) stages (7). An MSLT would show excessive sleepiness with N1 in most naps and a short sleep onset. It is often common to see N2 in 80% of the MSLT NAPS, and sleep-onset rapid eye movement periods (SOREMPs) can occur. As the MSLT can have two SOREMPs and a short sleep latency, ISS can be confused with narcolepsy along with other disorders of hypersomnolence. This confusion can be heightened with the epidemic we see of adolescents and young adults that frequently suffer from ISS. It is therefore important that a clear and accurate sleep history of normal sleep amounts be obtained.

Sleep fragmentation is best described as the interruption of sleep with frequent, brief arousals characterized by increases in EEG frequency or bursts of alpha activity and, occasionally, transient increases in skeletal muscle tone (41). These arousals generally last 3 to 15 seconds, usually do not result in prolonged wakefulness, and may not alter the sleep stage scoring of a standard 30-second epoch on a polysomnogram. Many times, the sleep technologist will be able to identify the arousing condition or stimulus (apneas, leg movements, and pain), and other times, no arousing stimulus will be identifiable.

Several studies have shown that sleep fragmentation without overall sleep loss per se is associated with reduced daytime function similar to that seen from acute sleep deprivation and TSD (42, 43, 44). Bonnet (42) evaluated this phenomenon by simulating the sleep-disrupting effects of apnea. This study involved performing a standardized awakening after each minute of sleep for two consecutive nights in normal adults. Following this experimental sleep disruption, subjects were significantly sleepier than they were at their baseline. The level of impairment was similar to that seen after periods of total sleep loss of 40 to 64 hours. In a similar study, Roehrs et al. (44) confirmed these effects. The latter study showed that brief EEG arousals on average of once every 4 to 5 minutes led to a 30% reduction in sleep latency, as measured by the MSLT during the following day. In addition, it was noted that as sleepiness increases, the threshold for arousal during subsequent nights rises as well.