Ask HN: Is anyone working on this? (Silent texts)

I understand instagram has something somewhat similar, but I was wondering if any of you all were working on the idea that you could send a late night text message to someone with their phone on alert without alerting their phone. Basically, allowing you to send late night texts without waking them up if it's not important, but still allowing you to send regular texts and wake them if it is. And do you think the idea has legs?