Risk factors for insomnia include female gender, having a previously diagnosed mental or physical health condition, being over age 60, stress, using certain medications such as stimulants, and having an irregular sleep schedule.11
Gender and Hormones
Women are more likely to struggle with insomnia than men due to hormonal changes during menstruation, pregnancy, and menopause. Sex hormones (eg, estrogen, progesterone, and testosterone) may significantly impact sleep, particularly in women. As many as 61% of postmenopausal women report symptoms of insomnia.21 Research suggests hormone replacement therapy in menopausal women can significantly improve sleep.22
Sleep disorders have been linked to lower testosterone levels in both men and women. In a cohort study of over 1,300 men aged 65 and older, subjects with lower testosterone levels had lower sleep efficiency (the percentage of time spent asleep while in bed) and increased night waking, although this association was largely explained by being overweight.23 Obesity and abdominal fat is associated with lower testosterone levels in men, and in turn, low testosterone levels may promote obesity.24 Low testosterone levels may also worsen overall sleep quality, which may improve with moderate levels of testosterone replacement therapy.25
Lower serum testosterone levels correlate with increased obstructive sleep apnea severity.26,27 Obstructive sleep apnea is most common in middle aged men, especially those who are overweight. People with obstructive sleep apnea have increased night waking, fragmented sleep, reduced sleep efficiency, and less rapid eye movement (REM) sleep, which in turn may lower testosterone levels.24 More research is required to understand causal relationships between sleep quality and testosterone levels, especially in older or obese individuals and those with chronic health conditions.
Obstructive Sleep Apnea—A Hidden Epidemic with Deadly Consequences
Obstructive sleep apnea is a common yet often overlooked sleep disorder that causes breathing to stop and start during sleep. It occurs when the throat muscles relax and block the airway, reducing oxygen flow. The resulting low oxygen levels in the bloodstream arouse the individual, resulting in disrupted sleep (even if they do not fully remember awakening). This pattern may be repeated five to 30 times an hour throughout the night.28 More than 18 million Americans have obstructive sleep apnea, causing poor sleep quality, snoring, mood changes, and intractable fatigue.29-31
Sleep apnea represents a major risk factor for cardiovascular disease, the leading cause of death in American adults, and is also linked to obesity.32 Obstructive sleep apnea has been associated with a 68% increase in coronary heart disease in men33 and may also be associated with increased cholesterol levels, hypertension,31,34 type 2 diabetes,35 cancer mortality,36 stroke, and death.28,37
For more information, refer to Life Extension’s Sleep Apnea protocol.
Comorbid insomnia may be a symptom of and contributor to many mental health problems, including anxiety, depression, schizophrenia, attention deficit hyperactivity disorder, and bipolar disorder.38-40 Patients with untreated insomnia are two to 10 times more likely to experience new or recurrent episodes of depression. A longitudinal study of people aged 65 and older in Japan found a statistically significant bi-directional relationship between insomnia and the development of depression.41
Studies indicate insomnia is a risk factor for the development of anxiety disorders and substance abuse as well.42 In one longitudinal study in adolescents, insomnia symptoms were associated with the use of alcohol, cannabis, illegal drugs, and suicidal ideation and attempts.43 Insomnia is also linked to certain personality traits, such as social introversion and the repression of feelings.44
One randomized controlled study found people who were sleep deprived showed more emotional reactivity to unpleasant images than those who were not sleep deprived, which suggests that sleep plays a role in emotional reactivity.45 In another controlled study of 14 people with chronic, primary insomnia, participants underwent an MRI scan during an emotional regulation task in which they were shown either negative or neutral imagery. They were asked to either view the images or use cognitive reappraisal techniques (in which you work to interpret the image as less negative in order to feel better about what you view) to decrease their emotional responses. Insomniacs showed higher levels of activity in the emotional processing area of the brain, suggesting they had neural circuity dysfunctions that impacted their ability to regulate emotions.46
Psychophysiological insomnia is a common type of chronic insomnia that can be very difficult to treat. It appears to be linked to hyper cortical arousal when going to bed. Psychophysiological insomnia is associated with excessive worrying at bedtime, specifically focused on not being able to sleep.47 Afflicted individuals have a hard time relaxing when they go to sleep, resulting in racing thoughts. They often focus on their difficulty falling asleep, which results in more anxiety that further disturbs sleep.
Over time, poor sleep and worries about sleeping can become associated with going to bed, resulting in a pattern of chronically poor sleep that affects daytime activities. Some believe that in addition to heightened arousal, individuals with psychophysiological insomnia may have some dysfunctional neurological inhibitory mechanisms that would normally help the mind "disengage" from daytime thought patterns.48
Treatment of psychophysiological insomnia includes good sleep hygiene practices, no daytime napping, limiting caffeine intake, cognitive behavioral therapy, and approaches that acknowledge worries (such as journaling or making a worry list). A recent longitudinal case series study with 60 subjects found that psychiatric comorbidities were strongly linked to negative treatment outcomes for people with psychophysiological insomnia, and people with strong social support and cognitive coping skills were most successful in treatment.49
Certain medical conditions can disrupt sleep, increasing the risk of insomnia. These include chronic pain conditions, asthma, heart failure, stroke, gastrointestinal issues, and an overactive thyroid.50
Most adults aged 65 and over require approximately seven to nine hours of sleep per night. However, people in this age group often struggle with insomnia.51 A poll by the National Sleep Foundation found that one in five adults aged 55‒84 years experienced difficulty falling asleep, and a quarter of this population reported waking early a few days per week in the past year. Sleep efficiency is known to decrease after age 60.52
Insomnia is associated with epigenetic aging, which reflects a person’s biological age based on DNA methylation. One review of data from the Women’s Health Initiative determined that insomnia symptoms were associated with advanced epigenetic age of blood tissues and higher amounts of late differentiated T cells (immune cells that trigger inflammatory responses). These results implicate sleep duration in accelerated aging.53
Medications and Stimulants
A wide variety of prescription medications can affect sleep patterns, and sleepiness is one of the most common reported side effects of medication use.54,55 Medication-induced insomnia can be caused by a wide variety of drugs, including decongestants, diuretics, antihistamines, monoamine oxidase inhibitors (MAOIs), selective serotonin reuptake inhibitors (SSRIs), corticosteroids, chemotherapeutic agents, calcium channel blockers, beta-agonists, and theophylline.56-59
While some medications can cause insomnia, others disrupt sleep patterns or cause daytime drowsiness.55 In addition, over-the-counter medications, such as pain, allergy, or cold medicines and weight-loss products, may contain stimulants that contribute to insomnia.11 If you think a medication may be disrupting your sleep, speak with your physician. They may switch you to a different medication or modify the dosage of your current medication.55
Caffeine. Caffeine is one of the most widely consumed stimulants in the world. Found most commonly in coffee and other drinks, caffeine is used to combat sleepiness and enhance performance. Stimulants make it harder for the brain to achieve the state of relaxation needed for sleep.
The half-life (ie, the amount of time it takes the body to break down 50% of a dose) of caffeine is between three and seven hours; larger amounts and/or repeated doses of caffeine lead to slowed caffeine clearance, causing the effects to last even longer.60 As a result, caffeine consumption can impair sleep for many hours. In a national survey that evaluated caffeine consumption and difficulty falling and staying asleep, amount of non-restorative sleep, daytime sleepiness, and typical duration of sleep attained per night, caffeine consumption was associated with insomnia symptoms, especially daytime sleepiness.61
Another review of randomized controlled trials and epidemiological studies found caffeine prolongs sleep latency (the amount of time it takes to transition from a wakeful state to sleep), reduces total sleep time and sleep efficiency, and worsens perceived sleep quality.62 Older adults may be more sensitive to the effects of caffeine. Most research suggests mild caffeine consumption in the morning does not impair sleep.63
Nicotine and smoking. The use of nicotine and nicotine replacement therapy as well as nicotine withdrawal can contribute to insomnia.64 One study analyzed 29 years of data from the Children and Adults in the Community Study to assess the prevalence of insomnia among heavy/continuous smokers, late-start smokers, occasional smokers, quitters/decreasers, and nonsmokers. The study found chronic smokers were more likely to develop insomnia symptoms later in life.65 Another review of data from over 83,000 people in the Behavioral Risk Factor Surveillance System indicates current smokers or smokeless tobacco users are twice as likely to have insufficient sleep as non-smokers and non-smokeless tobacco users, independent of age, sex, race, alcohol use, and body mass index (BMI). Secondhand smoke exposure was also associated with insufficient sleep among people who never smoked or who quit.66
Alcohol. While most people think of alcohol as a sedative, it increases dopamine release within the brain, which has a stimulating effect.67 Chronic alcohol use is associated with insomnia, as is alcohol withdrawal.68 A review of over 60 studies indicated 2‒3 drinks before bed may promote sleep, but this effect diminishes after three continuous days.69 Sleep disturbances are common among those who abuse alcohol, and are often associated with relapse.70 A study examining the prevalence of insomnia in 302 alcohol-dependent patients in a treatment program in Poland found that over 60% had symptoms of insomnia, with delayed sleep being the most common symptom. A history of childhood abuse, poor health, and severity of alcoholism were predictors of insomnia in this group.71
A longitudinal outcomes study including 267 subjects with alcohol-dependence issues found that at baseline, 47% of subjects were classified as having insomnia. Abstaining from or reducing alcohol intake reduced reported sleep disturbances, although insomnia persisted in 60% of cases, particularly in those with severe insomnia. Alcohol treatment programs should include insomnia evaluation during the treatment period to help focus care and prevent relapse.72
More information is available in Life Extension’s Alcohol: Reducing the Risks protocol.
People under stress often struggle with insomnia.73 Worries about finances, work, school, and family issues may cause a state of hyperarousal, making it difficult to relax into a restful sleep state. One study demonstrated that those who are vulnerable to cognitive and emotional hyperarousal may be more likely to experience stress-related insomnia.74 Stress can also decrease sleep quality.11 Major life events, such as job loss, moving, the birth of a child, death of a loved one, or divorce may also trigger a bout of insomnia.
Not all U.S. employees have a traditional 9 a.m. to 5 p.m. job. Nearly 10% of those with a non-standard work schedule (such as rotating shifts, on-call work, or permanent night shifts) have shift-work disorder, which is a disconnect between the body's circadian rhythm and the earth’s natural day-night cycle.75 An additional 30% of shift workers experience symptoms such as excessive sleepiness when they need to be awake and alert, insomnia, problems focusing, a lack of energy, and depression. Even shift workers who get enough sleep during the day may experience some of these symptoms, as their internal clock sends signals to indicate it is time to sleep during nighttime hours.76 Shift work may also be associated with increased risk of certain diseases, including cancer and heart disease.