When a jockey has the horse relaxed during the run, he is said to have put him/her to sleep.
This usually happens when the horse is ridden quiet towards the back of the field.
If the horse is relaxed during the run, it means they aren't wasting unnecessary energy, and have a better than fair chance of winning the race.
Note: Not to be confused with put him/her down, which is when the horse is euthanized.
"Purton has put her to sleep at the back of the field. Watch her run home!"
