I’m sure, you won’t be always sleepy in live-band cafe.
It’s the listener’s fatigue. The sound of your electric audio system is broken and severely distorted even if you don’t hear it. In fact, our ears and brain hear those bad sound always. They just convert these unlistenable sounds to enjoyable sounds. It’s the trick of human brain which needs 10-100 times more processing work than hearing the natural sound. This is hard work and you become sleepy.
Here’s proof. Your audio system sounds distorted/noisy like the left speaker below. Test your audio system saying "Hello" with your speaker sound like below. Alex/Wavetouch audio