Function and Quality of Life

Many researchers have addressed the question of how sleep and circadian problems affect not only personal ability to function, but also quality of life (QoL). Let’s take a look at some of these studies. 

• When researchers asked a large group of adults living in their homes about the impact of sleep quality on their QoL, researchers found that poor sleep quality affects not only emotional well-being, but also physical functioning.⁷
• When analyzing data from 27 studies of restless legs syndrome (RLS) and QoL, Broström et al⁸ found that mental and physical health components and overall QoL scores were low in patients with RLS, as compared with people without RLS.
• People with narcolepsy also have a low QoL in comparison to both the general population and people living with other chronic medical conditions, such as multiple sclerosis, diabetes, hypertension, and epilepsy.⁹
• According to the ARISE study, people living with idiopathic hypersomnia, regardless of whether they have long sleep time, have poor QoL and impaired functioning, including moderate to severe cognitive problems, moderate to severe depression, and high levels of absenteeism (when you can’t go to work) and presenteeism (being at work, but not functioning at an optimal level).¹⁰
• Among 34 older adults who answered questionnaires and wore actigraphy watches for 7 days, Stallings et al found that circadian rhythm sleep-wake disorders (CRSWD) were common (29%), particularly delayed sleep-wake phase disorder, and that QoL physical health scores were lower than in the general population.¹¹

Healthcare Impact and Cost

The impact on the healthcare system of untreated sleep and circadian problems is staggering. Many people endure repeated clinic and emergency department visits and unnecessary diagnostic tests and treatments before their sleep and circadian disorders are correctly diagnosed and treated, if ever. Faria concluded in a recent publication that the estimated costs of sleep disorders in the United States are approximately $130 billion per year.¹²

Here are some other shocking statistics:

• The annual indirect costs associated with untreated insomnia are estimated to be 10 times the costs to treat the insomnia.¹³
• The American Academy of Sleep Medicine (AASM) reported in 2016 that the annual cost of undiagnosed obstructive sleep apnea (OSA) is an astounding $150 billion annually.¹⁴

Researchers have also examined the costs of sleep and circadian problems. These costs include not only direct financial costs of treating the problems, such as medications and associated emergency department, inpatient, and outpatient visits, but also the economic burden to society (indirect costs), such as long- and short-term disability, presenteeism, and absenteeism.

• The AASM’s report regarding the annual cost of undiagnosed OSA included not only direct but also indirect costs. These include lost productivity and increased use of healthcare resources when OSA is undiagnosed; however, even when factoring in the cost of diagnosis and treatment, the report indicates that the annual economic savings would be in excess of $100 billion.¹⁴ 
• In a study conducted in Australia, researchers found that the costs associated with OSA, insomnia, and RLS were over $35 billion annually when including the financial (ie, health system, productivity losses, informal care, nonmedical accident costs, and deadweight losses) and nonfinancial costs, amounting to an excess cost of more than $16,000 per person per year for OSA and RLS each and more than $22,000 for insomnia.¹⁵

Work/Academic burden and cost 

Having a sleep problem or disorder can change a person’s education plans, choice of career, and career trajectory. For example, almost 30% of college students report having a sleep disorder. And most of the approximately 20-30% who report having trouble falling asleep or staying asleep have poor sleep quality and quantity. In a study of almost 300 college students that used validated questionnaires and clinical interviews, Gilstrap et al¹⁶ found that three-quarters of respondents reported having 1 or more sleep problems and that one-quarter met the diagnostic criteria for a sleep disorder. Those students who met the criteria for having a sleep disorder were more likely to have lower academic performance, missed classes due to illness, and a lower level of overall functioning. 

In another study that examined the impact of sleep disorders on work performance among young employed adults, 25% of the participants had a sleep disorder, 29% were shift workers, and 31% slept less than 6 hours per 24 hours (insufficient sleep). Working shifts and insufficient sleep were not associated with poorer work performance or QoL, but those with a sleep disorder had significantly lower mental and physical functioning and poorer work performance.¹⁷ In an earlier study, these same researchers found that sleep disorders are mostly undiagnosed in this group of working young adults.¹⁸ 

The Circadian Distribution of Disease

ALAN is not your friend! 

A two-way relationship exists between circadian disruption and our health. Studies in humans and animals have shown that exposure to artificial light at night (ALAN) combined with a lack of exposure to daytime sunlight is a major threat to human health and well-being. When our circadian rhythm (our body clock) is disturbed — such as from staying up late, working night or rotating shifts, exposure to ALAN, or not getting enough natural light during the day—we can develop health problems. 

Circadian Timing of Peak Likelihood of Disease or Exacerbation

Figure Legend:

This clock shows the times when medical conditions or death are likely to occur in a person who typically goes to bed about 10:00 pm and wakes up about 6:00 am. Adapted from Singh K, Poddar AS, Nigade SU, Poddar SS. Pulsatile drug delivery system. Int J Curr Pharm Rev Res. 2011;2(2):54-80.¹⁹

Studies that look at the rate of disease in a large population (epidemiologic studies) have identified ALAN as increasing the risk of a number of conditions, ranging from metabolic (obesity, metabolic syndrome, diabetes) and cardiovascular disease (hypertension, heart attack, stroke) to cancer (breast, prostate, colorectal, and others).²⁰ Circadian disruption has been shown to worsen neurodegeneration, and, conversely, neurodegenerative diseases such as Parkinson’s disease, Alzheimer’s disease, and rapid eye movement (REM) sleep behavior disorder can disrupt circadian rhythm. Sleep disorders, such as obstructive sleep apnea, insomnia, restless legs syndrome, and others, are associated with an increased risk of neurodegeneration. The key to reducing the risk of neurodegenerative diseases may lie in normalizing the circadian disruption and treating the underlying sleep disorders.²¹

In response to the World Health Organization’s warning that shift work at night is probably a carcinogen,²² researchers have conducted additional studies to try to identify why circadian disruption is so detrimental to health. Bonde et al²³ found that the risk of breast cancer is increased in women who work the night shift for 20 or more years. Possible reasons for this increased risk include

• Disturbed sleep patterns
• Reduced melatonin levels through nighttime exposure to artificial light
  • Melatonin helps to fight cancer 
  • When melatonin is suppressed by exposure to nighttime light, breast cancer tumors grow more quickly
• Deregulated circadian genes
  • For example, the expression of period genes is inhibited in breast and endometrial tumors
• A suppressed immune surveillance system that keeps an eye out for cancer cells in the body

Many diseases disrupt our sleep patterns, and when we are sick, our body clocks may not function properly, creating a vicious cycle of poor health and altered circadian rhythm.²⁴ 

For more information on how circadian rhythm and disease interact, see Across The Body.