Chrononutritional interventions, such as time-restricted feeding (TRF), have been extensively studied with an emphasis on metabolism. However, the evidence regarding the effects of TRF on sleep health remains fragmented and inconclusive. To add to the information in this area and given the potential connections between sleep and metabolic health and the diversity of TRF interventions, a meta-analysis of the effect of TRF on sleep will help to increase the level of evidence available on this topic. This meta-analysis presents the effects of TRF, including a specific type of TRF (Ramadan), on sleep, measured by subjective and objective methods. The review was conducted according to the PRISMA 2020 guidelines and registered in the PROSPERO database (CRD42020181264). The search was conducted in the databases MEDLINE, Scopus, Web of Science, EMBASE, LILACS and Cochrane CENTRAL until March 2024. The article selection process was conducted in two stages: first, the titles and abstracts were screened, and then the full texts were analyzed. The outcomes evaluated were self-reported total sleep time (TST), subjective sleep quality measured by the global score on the Pittsburgh Sleep Quality Index (PSQI), and objective TST measured by polysomnography or actimetry. The final sample included 51 articles from 17 countries, published between 2001 and 2023. The results showed that TRF decreased self-reported TST and impaired subjective sleep quality, as evidenced by an increase in the global score of the PSQI. Ramadan fasting significantly decreased TST and non-Ramadan TRF studies showed an overall increase in TST, suggesting that the timing and structure of dietary interventions play a crucial role in sleep health. Regarding PSQI, Ramadan fasting increased the global score, indicating poor subjective sleep quality. There was no statistically significant difference in the global PSQI score between the TRF and control groups in non-Ramadan fasting studies. Our results suggest that TRF has an effect on self-reported sleep duration and quality that depends on the type and duration of dietary restriction. Further randomized and controlled intervention studies are needed to better understand this relationship.
Circadian Biology