England head coach Brendon McCullum, director of cricket Rob Key and Test captain Stokes have previously rejected suggestions of a drinking culture, which Brook echoed on Wednesday.
However, England have now enforced a curfew, meaning players and staff have to be back on hotel premises by midnight.
“That’s been made as a group decision,” said Brook. “We think that it’s the best thing going forward, for the time being, to be able to put us in situations where we can win games of cricket and perform at the best of our ability.
“I don’t know what it’s like in other sports, but it’s probably a lot stricter in rugby, football and stuff like that. For the time-being, I think it’s fair enough.”
Brook was promoted to Stokes’ vice-captain in the Test team for the Ashes.
All-rounder Stokes has previously dealt with similar adversity, when he was involved in an altercation outside a Bristol nightclub in 2017. Stokes was subsequently charged with and cleared of affray but he missed the 2017-18 Ashes tour as a result of the incident.
“He obviously wasn’t best pleased at what I’d done, but he tried to help me through it,” said Brook of Stokes’ reaction.
“He knows exactly what it feels like to be in this situation. We had a few conversations, but we quickly moved on from that and tried to look forward to the Ashes.”
After England’s Ashes campaign was blighted by dropped catches, they have employed a fielding coach for the three T20s in Sri Lanka and the World Cup that follows.
Carl Hopkinson, who left the set-up when McCullum assumed control of the white-ball team at the end of 2024, returns on a short-term basis.
Zak Crawley will open the batting against Sri Lanka on Wednesday, winning his ninth ODI cap and first for more than two years.
Brook also confirmed 22-year-old Jacob Bethell would take charge of England’s white-ball teams if he is ever not available.
Bethell became the youngest man to captain England when he led the side in a T20 series in Ireland in September and made his maiden Test century against Australia in Sydney.