Insomnia: Nutritional Considerations
Healthy natural sleep should follow as a consequence of the normal physical and mental fatigue people typically experience during an active life. However, sleep deprivation is increasingly common, and it may be attributed to poor lifestyle choices. Chief among these are excesses of caffeine and alcohol and inadequate physical activity. Steps to be considered are discussed below.
Avoiding alcohol. Small amounts of alcohol (eg, 1 standard drink per evening) may not have negative effects on sleep for most people. However, people soon develop tolerance to its sedative effects, thus making it less useful for inducing sleep.10 Alcohol may increase the risk of insomnia by several mechanisms. Excess or chronic alcohol intake (ie, alcohol abuse or dependence) can decrease REM phase sleep in a dose-dependent manner.11 Alcohol consumption in the amount of 0.5 or 1.0 g/kg (3- 6 standard drinks) also causes disruption of normal circadian rhythms,12 probably through inhibiting melatonin secretion by more than 40%.13 Alcohol may cause rebound excitation through an increase in the number or sensitivity of receptors for glutamate, an excitatory neurotransmitter.12 As alcohol is metabolized, it produces aldehydes, which can have stimulating effects.14 Alcohol hangover, an excitatory state despite its reputation as one involving malaise, may be related to acetaldehyde.12 Alcohol may also increase the level of histamine, a known excitatory neurotransmitter, in the central nervous system (CNS).15
Limiting caffeine. Caffeine produces varying effects in individuals. In middle-aged persons drinking up to 7 cups of coffee per day (600 mg) and in subjects to whom caffeine was acutely administered, few or no effects on sleep were noted.3,16 However, some persons are more sensitive to the effects of caffeine, particularly elderly persons, who often unknowingly consume caffeine in over-the-counter medications.17 Slower blood clearance and higher blood concentrations of caffeine at midnight have been found in individuals with caffeine-related insomnia than in those not adversely affected by caffeine, indicating that differences in caffeine metabolism may be a cause of sleep disturbance.18 In persons with suspected or documented caffeine-sensitive sleep insomnia, discontinuing coffee alone may not be effective. This strategy may underestimate total caffeine intake from all sources, which include cola beverages, tea, chocolate, and medications.19
Avoiding milk if intolerant. Infants with cow's milk allergy have been found to have frequent arousals during sleep, shorter sleep cycles, and larger amounts of non-rapid eye movement (NREM) sleep with easy awakening. After elimination of cow's milk for several weeks, a significant decrease in the number of arousals occurred, while total sleep time and time spent in NREM2 and NREM3 sleep all increased significantly.20 Further study by the same researchers using double-blind, crossover methodology also found normalization of sleep in a group of children < 5 years of age.21 Although confirmation from other investigators is indicated before cow's milk elimination can be deemed proven for children with sleep disorders, it is a low-cost, no-risk strategy that can be tried before more invasive evaluation methods.
Carbohydrates. Tryptophan and 5-hydroxytryptophan are precursors of melatonin through the serotonin pathway, and have some efficacy in the treatment of insomnia. However, neither can be recommended, due to previous findings of contamination with a compound that has caused eosinophilia-myalgia syndrome (EMS).22 The passage of tryptophan across the blood-brain barrier depends on the extent to which it must compete with other amino acids. In this context, carbohydrate-rich foods may prove helpful. Over the short-run, they stimulate the release of insulin, which reduces blood concentrations of competing amino acids, fostering tryptophan's passage across the blood-brain barrier.23
Avoiding over-the-counter weight-loss products. Products that contain ephedra alkaloids (eg, Ma huang) in combination with caffeine have been increasingly used for weight loss, but they have been found to cause insomnia when compared with a placebo.24
Rectifying poor iron status. Insomnia is a frequent problem in patients with restless legs syndrome. Iron deficiency, even at levels insufficient to cause anemia, has been associated with this syndrome, and iron deficiency anemia is also associated with insomnia in pregnancy.25 Although more research is needed, available evidence implicates low brain iron concentration caused by the inadequate transportation of iron from the blood to the central nervous system as a cause of dopaminergic dysfunction in these patients.26 Iron supplementation was found effective for improving insomnia in teens with low iron stores.27
The following 2 supplements are under investigation for their roles in treating insomnia:
Melatonin. Disturbances in circadian rhythm and melatonin production are more common among both the elderly and shift workers, and evidence suggests that this can be partly ameliorated by supplemental melatonin. Although studies suggest that melatonin is safe and effective for treating delayed sleep phase syndrome, most evidence does not support its effectiveness for the majority of primary and secondary sleep disorders.28 However, melatonin appears to help patients, particularly the elderly, discontinue their reliance on benzodiazepines. This was found to be an effective strategy in 78% of patients using melatonin, compared with 25% using a placebo.29
Valerian. Valerian's sedative and hypnotic effects probably result from increases in the secretion of the neurotransmitter γ-aminobutyric acid (GABA) and inhibition of its uptake. Valerian binds to the same receptors as benzodiazepines, but with less efficiency and milder effects; this difference may account for the lack of residual morning sedation that is a common side effect of hypnotics.30 Doses of 400 to 500 mg/day have been found to significantly decrease sleep latency and improve subjective sleep quality. However, not all studies have found valerian to be effective. In addition, caution is warranted to avoid side effects, which may include headache, hangover, paradoxical stimulation, restlessness, and cardiac disturbances, as well as potentially dangerous interactions with barbiturates, benzodiazepines, opiates, and alcohol.30
What to Tell the Family
Insomnia can be caused by several factors, the most common involving caffeine and alcohol intake, lack of exercise, and poor sleep hygiene. When chronic, insomnia can adversely affect quality of life and should be discussed with a physician to rule out underlying medical or psychiatric etiologies.
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