title: The tryptophan depletion test: impact on sleep in primary insomnia - a pilot study.
abstract: The application of the tryptophan depletion test is based on the assumption that the decrease of plasma or serum tryptophan concentration following the ingestion of a tryptophan-free amino acid drink reflects a central nervous effect on serotonin metabolism. In the present study the impact of tryptophan depletion on polysomnographically recorded sleep in patients with primary insomnia was studied. Fifteen patients with primary insomnia slept for four nights in the sleep laboratory. Prior to the fourth night the tryptophan depletion test was applied. Sleep EEG variables served as outcome parameters. Patients with primary insomnia, compared to baseline values showed a highly significant decrease of serum tryptophan concentrations after the amino acid drink. Concerning sleep parameters, stage 1 (% sleep period time=SPT) was increased, whereas stage 2 (% SPT) was decreased. Indices of phasic activity of rapid eye movement (REM) sleep (REM density) were increased after the tryptophan depletion compared to baseline. The results suggest a negative impact of tryptophan depletion on sleep continuity and a stimulating effect on phasic measures of REM sleep in patients with primary insomnia.
authors.affiliation: Department of Psychiatry and Psychotherapy, University of Freiburg, Hauptstrasse 5, Germany. dieter_riemann@psyallg.ukl.uni-freiburg.de
authors.forename: Dieter
authors.initials: D
authors.lastname: Riemann
authors.forename: Bernd
authors.initials: B
authors.lastname: Feige
authors.forename: Magdolna
authors.initials: M
authors.lastname: Hornyak
authors.forename: Stephanie
authors.initials: S
authors.lastname: Koch
authors.forename: Fritz
authors.initials: F
authors.lastname: Hohagen
authors.forename: Ulrich
authors.initials: U
authors.lastname: Voderholzer
mesh_terms: D000328:Adult; D001921:Brain / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D017286:Polysomnography; D011237:Predictive Value of Tests; D012701:Serotonin / Q000502:physiology; D007319:Sleep Initiation and Maintenance Disorders / Q000175:diagnosis / Q000503:physiopathology*; D012894:Sleep Stages / Q000502:physiology*; D012895:Sleep, REM / Q000502:physiology; D014364:Tryptophan / Q000097:blood / Q000172:deficiency*
chemical_list: D012701:Serotonin; D014364:Tryptophan