This article is excerpted from Nutritional Medicine, a comprehensive textbook by Alan Gaby, MD. The book reviews the use of diet, nutritional supplements, and other natural substances for the prevention and treatment of more than 400 health conditions. It also includes 61 chapters on vitamins, minerals, amino acids, and other compounds, including biochemical effects, clinical indications, interactions, preparations, and dosage and administration.
Written for busy practitioners who need reliable but clinically-relevant information to guide patient care, Nutritional Medicine combines literature reviews, case reports, thorough background material and Dr. Gaby’s lifetime of clinical experience in applying nutritional approaches to manage complex disorders and to promote health and wellbeing. The book consists of 1,374 pages and more than 15,000 references, and is priced at $295. For further information, visit www.doctorgaby.com or call 603-225-01354.
Dietary Factors Affecting Sleep
Reactive Hypoglycemia & Food Allergy: Reactive hypoglycemia1,2 and food allergy3,4,5 have each been reported to cause insomnia. In my experience, many patients report that they sleep better after undergoing a nutritional program designed to improve blood glucose regulation or after identifying and avoiding allergenic foods.
Reactive hypoglycemia should be suspected particularly in patients who develop various symptoms in the late morning or late afternoon (before mealtime), who experience an improvement in symptoms after eating, and who crave sweets.
Food allergy should be suspected in patients who have other conditions that are frequently caused by food allergy, such as migraines, perennial rhinitis, or eczema. The evaluation and management of reactive hypoglycemia and food allergy are discussed in chapters 6 and 7, respectively.
Caffeine: It is well known that some people experience insomnia when they consume caffeine,6,7 particularly when they have it in the evening. Patients who suffer from anxiety appear to be more susceptible to the insomnia-inducing effect of caffeine than people without anxiety.8 Individuals with caffeine-induced insomnia metabolize caffeine more slowly than individuals who are not adversely affected by caffeine.
In one study, the mean plasma half-life of caffeine was significantly longer (7.4 hours vs. 4.2 hours; p < 0.05), and the mean plasma caffeine concentration 8 hours after ingestion of 2 cups of coffee was significantly higher, in people who experienced caffeine-induced insomnia than in those who did not.9 Among 10 self-rated poor sleepers, the longest caffeine half-life was 11.4 hours, compared with a maximum half-life of 4.8 hours among 10 normal sleepers.10
Thus, in some individuals a significant amount of caffeine will be present in the blood at bedtime, even if caffeine is consumed only in the morning. A trial of complete caffeine avoidance would therefore be worthwhile for patients who suffer from insomnia.
Helpful Nutritional Supplements for Sleep
L-Tryptophan: Tryptophan is a precursor to serotonin, which plays a role in normal sleep function. A number of clinical trials have found that supplementation with 1-2 g of L-tryptophan 20-30 minutes before bedtime improved insomnia.11,12,13,14 L-Tryptophan appears to be most effective for patients with mild insomnia, healthy individuals who have longer-than-average sleep onset latency (the amount of time required to fall asleep), and people who have clear awakenings 3-6 times during the night (see below). L-Tryptophan has also been reported to be effective for insomnia in chronic alcoholics.15
Some studies have found that L-tryptophan is not beneficial for insomnia. Factors that may explain these negative results include short duration of treatment and the type of insomnia being treated. One study in which L-tryptophan was not effective lasted only 2 days,16 but it may take up to 2 weeks before a beneficial effect is seen.17
In a study of patients with severe insomnia, those who reported clear awakenings 3-6 times per night showed a good response to L-tryptophan, whereas there was no improvement in patients who experienced clear awakenings 1-2 times during the night, or in those who reported dozing on and off throughout the night, twilight sleep, and a blurring between sleep and wakefulness.18
For best results, L-tryptophan should be administered on an empty stomach along with a small amount of carbohydrate. Taking L-tryptophan with a protein-containing meal would decrease its efficacy, because other amino acids present would compete with L-tryptophan for uptake into the brain. Co-administration of L-tryptophan and antidepressants that increase serotonergic activity (such as selective serotonin-reuptake inhibitors, amitriptyline, or monoamine oxidase inhibitors) may increase both the efficacy and the toxicity of the drugs.
If a patient is taking one of these medications, L-tryptophan should either be avoided completely (particularly in the case of monoamine oxidase inhibitors) or used with caution and in low doses.
Niacinamide: Administration of 3 g/day of niacinamide to 2 women with moderate-to-severe insomnia and to 6 individuals with normal sleep patterns resulted in a significant increase in rapid-eye-movement (REM) sleep in all cases. In addition, the women with insomnia experienced a marked improvement in sleep efficiency after 2-3 weeks of treatment.19 While the mechanism of action of niacinamide is not certain, it may work by increasing serotonin concentrations in the brain.
I have seen a few patients in whom supplementation with 1-2 g/day of niacinamide was beneficial for insomnia. A 68-year-old man came to my office with a life-long history of insomnia. He had seen numerous conventional and holistic practitioners, but had not found an effective treatment that did not cause side effects. Since the only nutritional treatment he had not tried was niacinamide, he was advised to take 1,000 mg during the day and again at bedtime. He experienced considerable improvement, and at his last follow-up visit 3 years later, was still sleeping well on the same regimen.
While niacinamide is generally well tolerated, administration of large doses has occasionally resulted in clinically significant elevations of aminotransferases (liver enzymes) and, rarely, chemical hepatitis (chapter 15). Patients taking large amounts of niacinamide (1,500 mg per day or more) should therefore have periodic tests to monitor liver function. Be very careful in the use of therapeutic doses of niacinamide in patients who have, or are at risk of developing, liver disease (such as chronic alcoholics).
L-Tryptophan & Niacinamide: Supplementation with niacinamide appears to increase the serotonergic effect of L-tryptophan by inhibiting the enzyme, tryptophan pyrrolase, which breaks down tryptophan in the liver (chapter 287). In my experience, the combination of L-tryptophan and niacinamide (500-1,000 mg of each, taken before bedtime) seems to be more effective for some than either of these nutrients alone.
Magnesium: Insomnia is one of the symptoms of magnesium deficiency.20 The typical Western diet contains less than the Recommended Dietary Allowance for magnesium. In addition, various types of physical and mental stress can lead to magnesium depletion and an increased magnesium requirement.21 For these reasons, many otherwise healthy people have suboptimal magnesium status.
In my experience, some patients experience improved sleep after beginning magnesium supplementation, usually 300-500 mg/day. While there are no studies examining magnesium as a treatment for insomnia, this mineral has been reported to improve sleep efficiency in patients with insomnia associated with restless legs syndrome or periodic limb movements in sleep.22
Vitamin B12: In case reports, 5 patients with chronic (> 18 months) disorders of their sleep-wake cycle improved after supplementation with 1,500-3,000 µg/day of vitamin B12. In some of these patients, the vitamin was administered as methylcobalamin, whereas in other cases the type of vitamin B12 used was not specified.23,24 However, in a double-blind trial, supplementation with 3,000 µg/day of methylcobalamin for 4 weeks was not beneficial for patients with sleep-wake cycle disorders.25
In my experience, some patients report improvements in sleep while receiving intramuscular vitamin B12 injections for various conditions (usually 1,000 µg every 1-4 weeks), although oral vitamin B12 supplementation is usually not effective.
Other Useful Treatments
Melatonin: Melatonin is a hormone secreted by the pineal gland that plays a role in regulating the sleep-wake cycle. Serum melatonin levels in normal humans are low during the day and increase significantly at night. Serum melatonin levels decrease with advancing age, and this decrease may contribute to the increased frequency of insomnia in elderly people. In elderly people with insomnia, peak melatonin levels were significantly lower and/or the onset of the peak level was delayed, when compared with age-matched subjects with normal sleep patterns,
Most,26,27,28 but not all,29 clinical trials have found that nighttime administration of melatonin is an effective treatment for age-related insomnia, delayed sleep phase syndrome, and pediatric sleep disorders, and for insomnia in patients with major depression30 or chronic schizophrenia.31 Melatonin was also used successfully to help patients withdraw from benzodiazepine therapy, without compromising sleep quality.32
While most studies used pharmacological doses of melatonin (2-5 mg at night), there is evidence that a physiologic dose (0.3 mg at night) is also effective for treating insomnia in elderly people. Pharmacological doses may induce hypothermia and may cause plasma melatonin levels to remain elevated into the daytime hours.33
The mechanism of action of melatonin in treating insomnia is not fully understood, although in some cases it appears to work by restoring circadian rhythms to normal. One study found that a dose as low as 0.1 mg had a hypnotic effect in healthy young men,34,35 whereas another study showed that 50 mg, but not 0.2 mg, had a sedative-hypnotic effect in elderly people.
Melatonin is usually well tolerated, but it may cause morning sleepiness, a reduction in sperm count, or other side effects. In addition, the long-term safety of using melatonin to treat insomnia is not known. Therefore, use the lowest effective dose, and try periodically to discontinue treatment. One study found that elderly people with delayed sleep phase syndrome (i.e., they could not fall asleep until 5 a.m.) who responded to 1-2 mg of melatonin at night, could successfully discontinue the treatment after 8 weeks without experiencing a return of their abnormal sleep patterns.
Valerian (Valeriana officinalis): The root of Valeriana officinalis (valerian) contains 2 substances that have sedative effects. In double-blind trials, administration of various valerian preparations decreased sleep onset latency and improved sleep quality.36,37,38 Valerian is typically taken 30-60 minutes before bedtime. The dosage varies according to the preparation used. Valerian is generally well tolerated, but there have been occasional reports of increased sleepiness the next morning.
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