There are 100 sleeps (100 days) until January 31 (Sunday, January 31, 2027).
There are 100 days until January 31 (Sunday, January 31, 2027) — 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 January 31. Sleeps are the same as days.
100 sleeps is 14 weeks and 2 sleeps.