Scientists have measured how much energy bacteria spend to hibernate and wake up. The study found that forming and reviving a spore costs nearly 10 billion ATP molecules, the cell’s energy currency.

The work was published in the Proceedings of the National Academy of Sciences. Researchers tracked the full energy budget of spore-forming bacteria step by step.

They found that outgrowth accounts for 88% of the energy used in revival. Waking up is far more costly than shutting down, the study shows.

The findings help explain how dormant bacteria survive harsh conditions for years. Spores can resist heat, chemicals and antibiotics while they sleep.

The researchers say the energy map could guide new ways to fight harmful spores in hospitals. More work is needed to test the idea in real settings. Spores are among the toughest life forms known. They can survive boiling, radiation and long years without food or water before springing back to life.