Insomnia: A Widespread Problem With Serious Consequences
Many medical and mental health problems are associated with insomnia
Posted Apr 15, 2019
In this post, I briefly review the causes of insomnia, a problem that affects one-third of adults and is associated with a variety of medical and mental health problems. In future posts, I will comment on the evidence for available mainstream treatments of insomnia, as well as complementary and alternative medical (CAM) treatments including herbals, non-herbal natural supplements, mindfulness, Chinese medicine, and others.
Disturbances of sleep affect all segments of the population
Approximately one-third of adults have problems sleeping such as difficulty falling asleep, early awakening, and interrupted sleep, and 5% meet diagnostic criteria for a sleep disorder. Individuals with chronic insomnia often experience daytime fatigue that interferes with their work performance. Disturbed sleep is an especially important problem among the elderly and people afflicted with mental illnesses. Almost 60% of individuals who seek mental health care report chronic insomnia and 75 percent of outpatients seen at specialized sleep clinics have at least one psychiatric disorder (Buysse et al., 1994). Insomnia can be caused by medical and mental health problems that directly or indirectly interfere with normal sleep. Twenty percent of children and 10% of adults experience recurrent nightmares. In industrialized countries, one-half of all cases of insomnia are probably related to psychological factors, including anxiety, depressed mood, chronic stress, and substance abuse. Pain syndromes, sleep apnea, neurological diseases, endocrinological imbalances, and circadian rhythm problems are common physiological causes of insomnia.
Many neurotransmitters are involved in sleep regulation
Many neurotransmitters contribute to normal sleep and wakefulness. Gamma-aminobutyric acid (GABA) inhibits the release of serotonin, norepinephrine, and other neurotransmitters that maintain wakefulness and is considered the most important regulator of sleep. Brain levels of norepinephrine increase with normal aging, possibly explaining the observed increased incidence of sleep fragmentation in the elderly. Hypocretin is a recently discovered neurotransmitter that probably plays a central role in maintaining normal wakefulness. Both GABA and hypocretin are synthesized and released from the hypothalamus, the part of the brain that regulates sleep and wake cycles in relation to the body’s circadian rhythms. In a normal sleep cycle, rapid eye movement (REM) sleep alternates with non-REM sleep in roughly 90-minute intervals throughout the night. REM and non-REM sleep periods are associated with characteristic electroencephalography (EEG) activity. Non-REM sleep normally predominates in the first hours of sleep, whereas REM sleep accounts for most of the final hours of sleep.
There are many causes of insomnia
Changes in an individual’s normal pattern of nighttime sleep or daytime wakefulness are often caused by medication side effects, substance abuse, and medical problems that directly or indirectly affect sleep-regulating neurotransmitters. Heart disease, diabetes, chronic pain syndromes, and respiratory illnesses are often associated with excessive daytime sleepiness or nighttime wakefulness. Disturbances in sleep occur more often in the elderly and medically ill compared with younger or healthy individuals and are frequently associated with depressed mood, chronic anxiety, and Alzheimer’s disease and other neurodegenerative diseases. Elderly individuals with severe insomnia experience more rapid cognitive decline compared with individuals with normal sleep (Cricco, Simonsick, & Foley, 2001). The complex relationships between disturbed sleep and depressed mood or other mental health problems have not been clearly established, but they may involve dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis affecting both mood and wakefulness (Richardson & Roth, 2001). Disturbed sleep is so commonly associated with a depressed mood that it is a diagnostic criterion of major depressive disorder. Approximately 90% of depressed patients and 70% of anxious patients complain of chronic insomnia, and almost half of individuals who report chronic insomnia meet diagnostic criteria for at least one psychiatric disorder. There is also a strong correlation between substance abuse and disturbances of sleep. Half of alcoholics report persisting insomnia.
Many prescription drugs deleteriously affect sleep. Many medications used to treat mental health problems adversely affect sleep. For example, psychostimulant drugs such as methylphenidate (Ritalin™) and so-called activating antidepressants such as bupropion (Wellbutrin™) and venlafaxine (Effexor™) often result in disrupted sleep; other antidepressants, including many selective serotonin reuptake inhibitors (SSRIs), cause daytime somnolence.
If you or a loved one struggle with insomnia it is important to seek care so that you can be properly evaluated and treated. Because of the large number of medical, psychiatric and other causes of insomnia, a thorough evaluation with a qualified health care provider is an important first step.