L-Tryptophan: Effects on Daytime Sleep Latency and the Waking EEG
Abstract
The essential amino acid, l-tryptophan, has been shown to reduce sleep latency when administered in doses ranging from 1-15 grams. Because l- tryptophan is regularly ingested in dietary protein foods, it has been called a 'natural hypnotic.' At least one author has suggested that plasma tryptophan, which shows a diurnal rhythm with peak levels in the late evening hours, may be a physiological regulator of sleep onset. However, not all researchers have found that l-tryptophan reduces sleep latency. There is also controversy about whether l-tryptophan administration alters the pattern of EEG-recorded sleep. Finally, the underlying mechanism for the putative hypnotic effects has not been well-established, although serotonergic systems are most likely involved. We conducted this study to determine the effects of l-tryptophan (4 g) on the waking EEG and on daytime sleep. Twenty normal, drug-free adults participated. Subjects were assigned to a morning or afternoon group, and data were collected on two occasions, after l-tryptophan and after placebo, assigned in a counter- balanced order. Blood samples were obtained by venepuncture and later analyzed for total and free tryptophan levels. Daytime nap sleep was recorded and scored according to usual procedures. Waking EEGs were digitized on-line and later analyzed for changes in five frequency bands: 16-40 Hz (beta), 13.0-15.5 Hz (sigma), 8.0-12.5 Hz (alpha), 4.0-7.5 Hz (theta), and 0.5-3.5 Hz (delta).
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 22, 1982
- Accession Number
- ADA123633
Entities
People
- Cheryl L. Spinweber
- Raymond P. Hilbert
- Reidun Ursin
- Richard L. Hilderbrand
Organizations
- Naval Health Research Center