Complications of Insomnia
Sleep is important to maintaining overall health and wellbeing, and chronic insomnia can have serious mental and physical health consequences. People with insomnia not only report a lower quality of life, but may also struggle with poor job and school performance, higher risk of automobile accidents, and physical diseases including heart disease, some cancers, and immunological conditions.11
Insomnia is associated with many medical conditions, which can directly or indirectly contribute to difficulty sleeping. Some health conditions frequently associated with insomnia include arthritis, asthma, urinary and gastrointestinal issues, sinus problems, endocrine abnormalities, and neurological conditions.51
Insomnia can also be a symptom of another underlying problem, such as sleep apnea or restless leg syndrome. Restless leg syndrome is a condition in which a person feels discomfort in the legs and a strong urge to move them. These urges can be strongest when trying to fall and stay asleep.51
A recent prospective study that followed nearly 5,000 people for 11 years concluded that insomnia was associated with a greater risk of cardiovascular disease.77 Another prospective study following nearly 55,000 people for 13 years found that insomnia was associated with an increased risk of heart failure. In this study, people with multiple insomnia-related symptoms had a higher risk of heart failure.78 A recent controlled study of nearly 4,000 subjects found a very short sleep duration (ie, less than six hours of sleep per night) was associated with an increase in subclinical atherosclerosis compared with those who slept six to seven, seven to eight, or more than eight hours per night. Those with more fragmented or interrupted sleep had more areas of atherosclerotic plaque.79
Sleep is also influenced by and has an influence on the immune system. A lack of sleep can weaken immunity, leaving one more susceptible to viral, bacterial, and parasitic infections.80 Research indicates sleep deficiency is associated with decreased immune function and increased levels of inflammatory markers, including interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α), which promote inflammation.
Insomnia affects the endocrine system.81 Steroid hormones may influence sleep, and the immune and endocrine systems may have a bidirectional relationship with sleep.80 Insomnia can lead to elevated levels of cortisol, epinephrine, and other stress hormones.82,83 Elevated levels of cortisol can cause weight gain, weaken the immune system, and increase the risk of developing diabetes and osteoporosis.84-86 Data from epidemiological studies indicate an association between sleep deprivation and serious metabolic and endocrine disorders, including diabetes and hormonal changes in the hypothalamus, pituitary, and adrenal axis.81
Insomnia has been associated with chronic pain and musculoskeletal issues. A controlled study of 34 people, half with insomnia and half without, found those with insomnia experienced pain twice as often as those without. The insomnia group had more frequent and intense pain, more sensitivity to heat and pressure, and a dysfunctional pain inhibition system.87 Researchers concluded that sleep quality is associated with the regulation of pain processing and ability to modulate pain. In a crossover study involving 14 healthy subjects who underwent a night of total sleep deprivation and a night of habitual sleep, researchers found that a night of sleep deprivation resulted in increased levels of sleepiness, anxiety, and sensitivity to heat and pressure.88