The Impact of 5-Hydroxytryptophan Supplementation on Sleep Quality of Older Adults in Singapore: A Randomized Controlled Trial

Abstract

Objectives

Sleep quality has been associated with a number of health conditions such as cognitive impairment and cardiovascular disease. 5-Hydroxytryptophan (5-HTP) is known as a precursor of the sleep regulating serotonin and melatonin. However, 5-HTP's efficacy for improving sleep in older adults is unclear. The aim of this study is to assess the impact of 5-HTP on sleep quality in older Singaporean adults.

Methods

This study is a single-blinded, 12-week parallel randomized controlled trial, where 20 older adults (67 ± 4 years, mean ± SD; 8 M, 12 F) were randomly assigned to either consume or not consume 100 mg 5-HTP daily. Sleep quality data were collected every 4 weeks via both subjective and objective measures such as Pittsburg Sleep Quality Index (PSQI) questionnaire and actigraphy watch. A global sleep score (GSS) was obtained from the PSQI, where a GSS > 5 has been validated to be associated with poor sleep quality. In addition, other sleep quality components that were also extracted include total sleep time (TST), sleep latency (SL) and sleep efficiency (SE). The main effect and interaction of 5-HTP on sleep were evaluated by repeated-measure analysis of variance (ANOVA).

Results

At baseline, subjects had an overall GSS of 5.9 ± 3.1 a.u. (5-HTP group: 6.3 ± 3.8 a.u.; Control group: 5.5 ± 2.3 a.u.) and this indicated poor sleep quality. Consumption of 5-HTP after 4 and 8 weeks showed a favorable decrease in their objective SL (SL_Obj) from their baseline (week 4: −18.2 ± 21.1 min; week 8: −17.8 ± 19.2 min). On the other hand, the control group did not display desirable change in SL_Obj (week 4: 2.4 ± 21.6 min; week 8: 1.5 ± 21.4 min). Repeated-measures ANOVA revealed a significant treatment-by-time effect between 5-HTP consumption and SL_Obj at week 4 (P = 0.045) and week 8 (P = 0.033), but not at week 12 (P = 0.135). A significant treatment-by-time decrease in subjective TST (−0.1 ± 0.4 hrs, P = 0.027) observed at week 12. No changes in GSS and other subjective and objective measures of sleep quality were detected.

Conclusions

Older adults had poor sleep quality and 5-HTP supplementation helped reduce sleep latency for up to 8 weeks. Prolonged effects were not observed, and this may be due to acclimation of the body to longer-term 5-HTP supplementation.

Funding Sources

NUS iHealthtech Microbiome in Health, Disease and Ageing.