There are 51 sleeps (51 days) until December 13 (Sunday, December 13, 2026).
There are 51 days until December 13 (Sunday, December 13, 2026) — one sleep per night.
One sleep per night between now and the big day — tonight is the first sleep, and the morning after the last sleep is December 13. Sleeps are the same as days.
51 sleeps is 7 weeks and 2 sleeps.