Simulated effects of microgravity, created by 60 days of constant bed rest, severely disrupts rhythmic gene expression in humans, according to a new study from the University of Surrey published in iScience.

Astronauts exposed to microgravity experience changes to physiology, including immune suppression, increased inflammation, and reduced muscle mass and bone density. With the increase in human spaceflight, it is important to understand changes in the molecular mechanisms underlying these changes.

Lead author Professor Simon Archer, Professor of Molecular Biology of Sleep at the University of Surrey, said, "This unique study represents the largest longitudinal dataset of time series gene expression in humans. Human gene expression varies rhythmically over the 24-hour day, and it is important to collect time series data rather than from just single time points to get a full picture of what occurs in the body when exposed to simulated microgravity.

"It also raises questions about the impact of constant bed rest on our bodies as we have identified a dramatic effect on the temporal organization of human gene expression.