Indian Air Force pilots are popping authorised pills to boost alertness and manage fatigue, the Times of India reported.
Two types of drugs are used - the "Go" Modafinil pills, which help keep pilots awake and active for long operations; and the "no-Go" Zolpidem, a sedative to help them sleep between missions.
They were used extensively in an annual military exercise, named Livewire, conducted from Oct 31 to Nov 8, 2015, the Times of India reported on Monday (Feb 8).
"Hundreds of missions were flown with impeccable planning and execution" during the nationwide exercise, said a Ministry of Defence press release last November.
The Times of India reported, quoting an unnamed senior IAF officer: "The Go/No-Go pills are being used to optimise performance only after extensive clinical trials, both in simulators and actual flying, with all necessary safeguards."
Doctors conducted field trials "to validate pharmacological strategies for sleep and alertness management for aircrews in extended operations", the officer added.
Both the pills helped to boost military personnel's performance, he said.
The use of pharmaceuticals to enhance the endurance of soldiers is not new.
Modafinil began as an experimental treatment for narcolepsy.
The US army has been using it since the 2003 Iraq invasion, and France routinely supplies it to its fighter pilots, online magazine Slate reported in 2013.