Time-of-day as a critical biological variable

Area of Science:

• Behavioral neuroscience
• Chronobiology
• Animal models in research

Background:

• Time-of-day is a critical biological variable often neglected in biomedical research.
• Nocturnal rodents, common animal models, are typically tested during their light (rest) phase.
• This practice may introduce variability and compromise study findings.

Purpose of the Study:

• To assess the reporting of time-of-day in highly cited behavioral neuroscience studies.
• To highlight the implications of ignoring temporal factors in animal research.
• To emphasize the need for standardized reporting of experimental timing.

Main Methods:

• Systematic review of the top 25 most cited papers across key behavioral neuroscience domains.
• Analysis of reporting practices concerning the time-of-day for behavioral testing.
• Evaluation of methodological details related to temporal aspects of experiments.

Main Results:

• The majority of reviewed studies reported behavioral testing during the light phase, not optimal for nocturnal rodents.
• Time-of-day is infrequently considered in data analysis or detailed in publications.
• Few studies report measures to mitigate extraneous light exposure during dark-phase testing.

Conclusions:

• Failure to account for time-of-day in research design and reporting can hinder result replication.
• Ignoring temporal variables may reduce the translatability of animal study findings to humans.
• Standardized reporting of time-of-day is essential for advancing behavioral neuroscience research.