Tryptophan's Role in Cardiorespiratory Regulation in Sleep Disordered Breathing
Current research does not support the use of tryptophan supplementation for managing sleep disordered breathing, as evidence regarding its effects on cardiorespiratory regulation is limited and insufficient to recommend clinical use.
Existing Evidence on Tryptophan and Sleep Disordered Breathing
In a small study of 15 subjects with sleep apnea, L-tryptophan (2500 mg at bedtime) showed significant improvement in obstructive sleep apnea but not central sleep apnea, with most dramatic improvements seen in subjects with obstructive sleep apnea during non-REM sleep 1
A combination of trazodone and L-tryptophan demonstrated dose-dependent reductions in respiratory events in both non-REM and REM sleep in an animal model (English bulldogs) of obstructive sleep apnea hypopnea syndrome 2
The American Academy of Sleep Medicine specifically recommends against using tryptophan for treating sleep onset or sleep maintenance insomnia in adults (weak recommendation) 3
Mechanisms and Theoretical Basis
Serotoninergic activity with a potential defect in feedback control of tryptophan-serotonin metabolism has been postulated as a mechanism in the pathophysiology of obstructive sleep apnea 1
Tryptophan supplementation may enhance slow-wave sleep and minimize sleep-related suppression of upper airway dilator activity, which could theoretically benefit patients with obstructive sleep apnea 2
Sleep disordered breathing is characterized by repetitive periods of cessation in breathing (apneas) or reductions in breath amplitude (hypopneas) during sleep, often associated with sleep fragmentation, oxygen desaturation, and sympathetic nervous system activation 4
Current Treatment Recommendations for Sleep Disordered Breathing
Positive airway pressure (PAP) therapy remains the initial treatment of choice for sleep disordered breathing, particularly obstructive sleep apnea 4, 5
Weight loss (if obese) and exercise are recommended non-pharmacological approaches for managing obstructive sleep apnea 5
For sleep disordered breathing associated with specific conditions like sickle cell disease, a comprehensive sleep history and review of systems are essential to identify patients who should undergo formal sleep testing 3
Limitations of Current Evidence
Clinical trials with L-tryptophan for sleep disordered breathing are limited, with most studies having small sample sizes and methodological limitations 1, 2
The American Academy of Sleep Medicine guidelines note that wake after sleep onset was reduced by only 10 minutes with L-tryptophan compared to placebo, which is not clinically significant 3
No large-scale randomized controlled trials have evaluated the long-term efficacy and safety of tryptophan supplementation for cardiorespiratory regulation in sleep disordered breathing
Clinical Implications and Future Directions
Despite theoretical mechanisms suggesting potential benefit, there is insufficient evidence to recommend tryptophan supplementation for managing cardiorespiratory aspects of sleep disordered breathing 3
Further research is needed to determine if tryptophan supplementation could be beneficial as an adjunctive therapy in specific phenotypes of sleep disordered breathing
The relationship between sleep disordered breathing and cardiovascular outcomes is well-established, but interventions targeting this relationship have shown mixed results in improving cardiovascular outcomes 5