Premanand Maharaj Ji
How can I stop feeling sleepy and lazy during bhajan?
Sleep six hours, then fight drowsiness
Six hours of sleep is necessary for a healthy body, so give sleep its full time and then do not let laziness waste the rest. If drowsiness comes during bhajan, you have to fight it to win over it.
Give sleep its due in its own time. Give six hours to sleep, and after that, fight it.