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What is insomnia?
Insomnia is a sleep-wake disorder that causes difficulty falling and/or staying asleep (1).
It is considered chronic (long-term) if symptoms last at least 3 months, or acute (short-term) if symptoms last less than 3 months (2).
How common is insomnia?
An estimated 10-15% of adults meet the criteria for chronic insomnia, while another 25-35% have occasional insomnia (3).
Women are more approximately 1.5 times more likely than men to be diagnosed with insomnia (4).
The elderly tend to have higher rates of insomnia (12-20%) (5).
What causes insomnia?
There are two different types of insomnia with different causes.
Insomnia with no known cause is called primary insomnia (6).
The exact mechanisms behind primary insomnia are unclear, but the following factors have been proposed to play a role (7):
Insomnia has often been considered a disorder of hyperarousal, meaning that the body is in a heightened state of physiologic or cognitive activity (7).
People with hyperarousal-related insomnia often report having racing thoughts or feeling like they can’t “turn off” their minds.
Abnormal neurological functioning and imbalanced hormones, particularly cortisol, may play a role in hyperarousal (7).
Approximately 35% of patients with insomnia have a first-degree relative with a history of insomnia (9).
3. Cognitive/behavioral factors
The “3P model” suggests that predisposing, precipitating, and perpetuating factors contribute to insomnia (11).
According to this theory, predisposing factors, such as hyperarousal and anxious personality, increase the likelihood that a person will develop insomnia.
Then, precipitating factors (stressful situations, life changes, etc.) trigger the initial onset of acute insomnia.
Over time, chronic insomnia develops due to changes in behavior that inhibit sleep, such as napping or going to bed too early.
Approximately 85-90% of patients with chronic insomnia have comorbidities such as depression, anxiety, or other medical conditions (12).
When a patient’s sleep disturbances can be explained by a medical condition or other cause, this is called secondary insomnia.
What are some of the risk factors for developing insomnia?
1. Certain medical conditions
- Cardiovascular disease
- Chronic pain
- Obstructive sleep apnea
- Restless leg syndrome
2. Mental health disorders
- Bipolar disorder
3. Medications (16)
- ACE inhibitors
- Angiotensin receptor blockers (ARBs)
- Dopamine agonists
- Tricyclic antidepressants (TCAs)
- Serotonin and norepinephrine reuptake inhibitors (SNRIs)
- Selective serotonin reuptake inhibitors (SSRIs)
4. Other factors
- Caffeine intake (17)
- Gut dysbiosis (18)
- Low socioeconomic status (19)
- Sedentary lifestyle (20)
- Shift work (21)
- Stress (22)
- Substance abuse (23)
- Smoking (24)
How is insomnia diagnosed?
Insomnia disorder (also known as primary insomnia) is diagnosed according to the following DSM-5 criteria (2):
- Complaint of dissatisfaction with sleep quantity or quality occurs at least 3 nights per week for at least 3 months, associated with one or more of the following symptoms:
- Difficulty falling asleep.
- Difficulty staying asleep, with frequent awakenings or problems falling back asleep.
- Early morning awakening with inability to fall back asleep.
- The sleep disturbance causes clinically significant distress or impairment in social, occupational, educational, academic, behavioral, or other important areas of functioning.
- The sleep difficulty occurs despite adequate opportunity for sleep.
- The insomnia is not better explained by and does not occur exclusively during the course of another sleep-wake disorder (narcolepsy, a breathing-related sleep disorder, a circadian rhythm sleep-wake disorder, a parasomnia).
- Coexisting mental disorders and medical conditions do not adequately explain the predominant complaint of insomnia.
- The insomnia is not attributable to the physiological effects of a substance (a drug of abuse, a medication).
A sleep study (also called polysomnography) may also be performed to rule out other sleep disorders, such as sleep apnea (25).
Polysomnography measures brain waves, eye and body movements, blood oxygen level, and nasal airflow (26).
What are the potential health consequences of chronic insomnia?
1. Impaired performance & accidents
There is evidence that sleep loss impairs the ability to make good decisions and manage complex tasks while increasing risky decision-making (27).
In the United States, lost productivity due to insomnia costs employers an estimated 59.8 billion dollars every year (28).
2. Psychiatric conditions
However, it’s unclear whether insomnia is the cause or the effect in this situation, although it could be a combination of both (33).
4. Impaired immunity
Sleep strengthens the immune system by improving the functioning of T cells, a type of white blood cell that plays an important role in adaptive immunity (36).
5. Insulin resistance
Sleep deprivation has been shown to increase insulin resistance and impair glucose metabolism (40).
The risk of developing type 2 diabetes increases 9% for each hour of lost sleep below 7 hours per night (41).
It’s unclear exactly why this occurs, but it may be related to hormone disruption and increased inflammation (40).
Insomnia and short sleep duration (<6 hours/night) is associated with a higher risk of obesity, especially central (abdominal) obesity (42).
It is thought that sleep loss promotes weight gain by disrupting glucose homeostasis, appetite regulation, and hormone balance (43).
7. Cardiovascular disease
Insomnia is associated with an increased risk of cardiovascular disease, including hypertension, coronary heart disease, and heart failure (44).
Underlying mechanisms might involve hypothalamic-pituitary-adrenal (HPA) axis dysregulation and increased inflammation (44).
Short sleep duration (<5-7 hours per night) is linked with a 12% increase in the risk of death from all causes (45).
Interestingly, long sleep duration (>8-10 hours per night) is associated with a 30% greater risk of death (45).
What medications are used to treat insomnia?
Although medications can offer quick relief from insomnia, they are not recommended for long-term use because of the potential for side effects, tolerance, and dependency (46).
1. Benzodiazepines & benzodiazepine agonists
Benzodiazepines and benzodiazepine agonists are drugs that reduce anxiety and promote sleep by enhancing the effects of GABA, a neurotransmitter that reduces brain activity (47).
There are five benzodiazepines that are approved to treat insomnia: estazolam, flurazepam, quazepam, temazepam, and triazolam (48).
Benzodiazepine agonists used for insomnia include zaleplon, zolpidem, and eszopiclone (48).
2. Orexin receptor antagonists
Orexins (orexin A and B) are neuropeptides produced by the hypothalamus that help to regulate the sleep-wake cycle (49).
Suvorexant is a drug that blocks orexin receptors to prevent orexin from binding and suppresses wakefulness (50).
3. Melatonin agonists
Melatonin is a sleep-promoting hormone produced by the pineal gland (in the brain).
The drug ramelteon helps to decrease the amount of time required to fall asleep by enhancing the effects of melatonin (47).
4. Histamine receptor antagonists
Histamine is a chemical released by mast cells in response to allergic or inflammatory reactions and promotes wakefulness.
An antidepressant drug called doxepin can be prescribed to treat insomnia in low doses, because it blocks the binding of histamine to its receptors, resulting in a sedative effect (47).
5. OTC sleep aids
Most over-the-counter sleep aids contain antihistamine drugs, such as diphenhydramine or doxylamine, which are not recommended for insomnia because evidence supporting their effectiveness is lacking (51).
What is the most effective treatment for insomnia?
It involves the use of several techniques (listed below) to change behavior and thoughts surrounding sleep (52):
- Stimulus control is used to retrain the brain to associate the bedroom with sleep instead of anxiety, frustration, etc.
- Sleep restriction limits the amount of time spent in bed in order to increase the patient’s physiological sleep drive and improve sleep efficiency (time in bed spent actually sleeping).
- Paradoxical thinking requires patients to try to stay awake for as long as they can, which is supposed to reduce anxiety and help them fall asleep.
- Relaxation techniques include progressive muscle relaxation, breathing exercises, and meditation.
- Constructive worry exercises ask patients to list out whatever is causing them stress in the evening and write down what they will do to reach a solution the next day.
Strong evidence shows that CBTI significantly improves insomnia severity, sleep efficiency, the amount of time required to fall asleep, and subjective sleep quality, while increasing total sleep time by an average of 20 minutes (53, 54, 55, 56, 57).
To find a certified CBTI practitioner near you, use The International Directory of CBT-I Providers.
However, there are relatively few CBTI certified practitioners, so the following online treatment programs might be a better option for many patients:
- Sleepio is a fully automated web-based program with personalized recommendations based on information you provide.
- Somly offers a personalized program, including weekly phone calls with a sleep expert and online lessons to watch at your own pace.
- Somryst is an app designed to walk you through the program under the supervision of a clinician.
Do certain diets help improve sleep?
The following diets may be beneficial for insomnia:
1. Mediterranean diet?
However, clinical trials are needed to determine whether implementing a Mediterranean diet could improve symptoms in patients with insomnia.
2. DASH diet?
A 2019 study found that adolescent girls who had a higher adherence to the DASH diet were less likely to have insomnia (62).
More research is needed to confirm this link in other populations.
Which foods are beneficial for sleep?
The following foods may help facilitate sleep:
1. Tart cherry juice
Total sleep time increased by an average of 84 minutes in one of the studies (63).
Most of the studies used Cheribundi brand tart cherry juice, which contains the equivalent of 50 cherries per cup and isn’t made from concentrate like most other brands.
Kiwi are rich in serotonin and antioxidants, both of which may have a positive effect on sleep (66).
One small study that found that sleep duration and efficiency improved significantly after participants consumed 2 medium-sized kiwi one hour before bedtime every night for 4 weeks (66).
However, there was no control group, so it’s possible that the placebo effect interfered with results.
3. Fatty fish?
One study suggests that the consumption of fatty fish (10 ounces of salmon, 3 days/week) might improve sleep in healthy individuals (67).
The authors noted that vitamin D might have been responsible for these effects, as levels did improve throughout the study.
Which foods or supplements should be avoided before bedtime?
The following foods and supplements may interfere with sleep and should be avoided before bedtime:
Several trials have shown that cutting out caffeine for one day significantly improves sleep duration and quality (70).
Individuals who are highly sensitive to caffeine might benefit from complete caffeine abstinence (71).
However, there isn’t enough evidence to recommend that habitual caffeine consumers completely cut out caffeine in order to improve sleep (68).
Still, it’s best to avoid caffeine for at least 6 hours prior to bedtime (72).
Although alcohol is commonly used as a sleep aid, research shows it might not be as effective as it seems.
When healthy, non-alcohol-dependent individuals drink moderate amounts of alcohol before bedtime, the time it takes to fall asleep is reduced, and sleep quality is improved during the first half of the night (73).
Which nutrients are involved in sleep?
The following nutrients are important for sleep:
Glycine is a non-essential amino acid that may promote sleep by regulating circadian rhythm and body temperature (75).
Magnesium may play a role in sleep by increasing melatonin secretion and enhancing the effects of GABA (79).
In one study, magnesium also increased melatonin concentration while decreasing serum cortisol levels (80).
More research is needed to determine if these effects translate to younger individuals as well.
4. Vitamin D?
Individuals with vitamin D deficiency (serum 25(OH)D <20 ng/mL) have a more than 50% increased risk of sleep disorders, poor sleep quality, and short sleep duration (86).
However, high quality evidence to support the use of vitamin D for insomnia or other sleep problems is lacking.
In addition, there have been many anecdotal reports of new-onset sleep disturbances after starting vitamin D supplementation.
A 2016 trial did show that sleep quality DECREASED as postmenopausal women with vitamin D deficiency improved serum 25(OH)D levels to >32 ng/mL (87).
It’s unclear why this might occur, although one small study did find that high-dose vitamin D supplements (4,370 IU/day) significantly decreased melatonin levels (88).
Interestingly, lower doses (800 IU/day) did not have the same effects.
Do any supplements help promote sleep?
Research shows that the following supplements may help promote sleep:
Melatonin is a hormone secreted in response to darkness that helps to promote sleepiness (89).
One meta-analysis found that melatonin reduced sleep latency (time required to fall asleep) by 7 minutes and increased total sleep time by 8 minutes (90).
Melatonin should not be taken alongside sedative medications (such as benzodiazepines) (93).
Withania somnifera (also called ashwagandha) is an adaptogenic herb that is used to reduce stress and may promote sleep by enhancing GABA (94).
A 2019 trial in patients with insomnia showed significantly shorter sleep latency and improved sleep efficiency (from 76% to 84%) after ashwagandha root extract supplementation (300 mg twice daily) for 10 weeks (95).
Ashwagandha should not be taken with immunosuppressants or sedative medications (98).
Passionflower is an herb that is sometimes used as a sleep aid due to its sedative and anti-anxiety effects (99).
A 2020 trial showed a 20 minute increase in total sleep time in patients with insomnia who received passionflower extract supplements (60 mg/day) for 2 weeks (100).
More research is needed to confirm these results.
Passionflower should not be taken with sedative medications (101).
Cannabidiol (CBD) is one of the active components of the cannabis plant, also known as marijuana.
It does not contain tetrahydrocannabinol (THC), which is the psychoactive chemical found in cannabis that causes people to feel “high.”
Valerian is an herb that enhances the effects of GABA and has traditionally been used to promote sleep (105).
A large meta-analysis showed statistically significant improvements in insomnia in patients who received valerian root extract supplements (400-600 mg/day) (105).
However, the improvements were subjective (based on patients’ perceptions) and not clinically significant (0.7 minute reduction in time to fall asleep).
Valerian should not be taken with alcohol, alprazolam (Xanax), or sedative medications (106).
L-theanine is an amino acid found mainly in green tea that has been used to promote relaxation (107).
It might improve sleep by increasing serotonin and GABA levels (107).
However, research is needed in patients who have insomnia or other sleep disturbances.
L-theanine should not be taken with antihypertensive medications, because it may lower blood pressure too much (110).
Chamomile is an herb known for its sedative effects.
It contains apigenin, a flavonoid that binds to benzodiazepine receptors in the brain to promote sleepiness (111).
There is some evidence that chamomile supplementation may improve sleep quality in subjects with sleep problems related to old age, menopause, or chronic disease (112).
However, the only study in patients with primary insomnia showed no significant effects of chamomile (270 mg twice daily) on sleep (113).
8. 5-HTP + GABA?
5-HTP (5-hydroxytryptophan) is a metabolite of tryptophan and a precursor for serotonin (114).
In research, it has been combined with GABA, a neurotransmitter that inhibits neural activity, to promote sleep (115).
Research in humans is needed to confirm these results.
Patients taking antidepressants should not take 5-HTP, because it could increase serotonin too much and lead to heart problems (119).
What other lifestyle changes are recommended for insomnia?
1. Exercise regularly.
More research is needed to determine whether other types of exercise, such as resistance training, are also effective.
2. Increase bright light exposure during the day.
Exposure to bright light in the morning and throughout the day alters circadian rhythm (the biological clock that controls the sleep-wake cycle) (122).
Light therapy has been shown to be effective in treating insomnia, although the clinical significance is limited, suggesting that it is best used along with other treatments (123).
Most of the time, going outside offers plenty of bright light exposure, but some people choose to purchase light therapy lamps.
3. Restrict blue light exposure at night.
Blue light is visible light that has short wavelengths and is emitted by the sun, as well as light bulbs and electronic devices.
There is evidence that two hours of blue light exposure in the evening significantly suppresses melatonin, although levels increase within 15 minutes of blocking or removing the light source (124).
4. Diffuse essential oils.
Lavender is commonly used in aromatherapy and is thought to promote relaxation and reduce anxiety.
5. Practice mindfulness meditation.
Mindfulness meditation is the practice of being fully present in the moment and eliminating judgment.
Results from a 2016 meta-analysis show that mindfulness meditation significantly improved total wake time and sleep quality in individuals with insomnia, although total sleep time was not affected (128).
The authors concluded that mindfulness meditation might be a beneficial tool when used in conjunction with other insomnia treatments.
6. Try progressive muscle relaxation.
Progressive muscle relaxation(also known as Jacobson’s relaxation technique) involves tensing different muscle groups and relaxing them slowly while focusing on breathing (129).
Limited evidence shows improved sleep quality following the use of this technique (130).
Amy is a registered dietitian nutritionist and experienced nutrition editor. She received her Masters in Nutrition Diagnostics from Cox College and her Bachelors in Dietetics from Missouri State University. She currently works as a nutrition editor for Healthline and Greatist. Her passion is finding ways to communicate nutrition research in an interesting and easy-to-understand way.