# Supplementation of essential amino acids suppresses age-associated sleep loss and sleep fragmentation but not loss of rhythm strength under yeast-restricted malnutrition in Drosophila

## TL;DR

Adding essential amino acids to a low-protein diet in fruit flies improves sleep quality during aging but does not restore sleep rhythm strength.

## Contribution

The study shows that essential amino acid supplementation can specifically improve age-related sleep issues in a low-protein diet context.

## Key findings

- A malnutrition diet with restricted yeast reduced TOR signaling and lifespan in male fruit flies.
- Essential amino acid supplementation improved age-associated sleep loss and fragmentation but did not restore sleep rhythm strength.
- The sleep benefits of amino acids were independent of TOR signaling and lifespan extension.

## Abstract

Sleep quality and quantity decrease with age, and sleep disturbance increases the risk of many age-associated diseases. There is a significant relationship between nutritional status and sleep outcomes, with malnutrition inducing poor sleep quality in older adults. However, it remains elusive whether, and if so how, nutritional supplementation prevents age-associated sleep problems. Here, we utilized Drosophila to investigate the effects of a malnutrition diet with restricted yeast, a primary protein source, and supplementation of 10 essential amino acids (EAAs) on sleep profiles during ageing. Compared with the standard diet containing 2.7% yeast, the malnutrition diet containing 0.27% yeast significantly decreased target of rapamycin (TOR) signalling and shortened the lifespan of male Canton-S flies. By contrast, age-associated sleep loss, sleep fragmentation and loss of rhythm strength were similarly observed under both diets. Supplementation of the malnutrition diet with EAAs in restricted yeast significantly ameliorated age-associated sleep loss and sleep fragmentation without altering loss of rhythm strength. It also rescued decreased TOR signalling activity but not the shortened lifespan, suggesting that the effects of EAAs on sleep integrity are independent of TOR activity and lifespan regulation. These results may help to develop dietary interventions that improve age-related sleep problems in humans.

Graphical Abstract