Where does “sleepness” come from?

sleepness (English) comes from English sleep, from Middle English slepen, from Old English slǣpan, from Proto-West Germanic slāpan, from Proto-Germanic slēpaną, from Proto-Indo-European slab- — to be weak, be languid; be weak, limp, languid.

sleepness (English): The state, condition, or instance of sleeping;...

Definitions

  1. The state, condition, or instance of sleeping;...

Ancestry of “sleepness”, step by step

sleepness traces back through two separate lines of ancestry.

via English sleep

StepLanguageWordMeaning
1EnglishsleepTo rest in a state of reduced consciousness; To...
2Middle Englishslepento sleep; to become asleep, to cause to sleep; to...
3Old Englishslǣpan
4Proto-West Germanicslāpanto sleep
5Proto-Germanicslēpanąto sleep
6Proto-Indo-Europeanslab-to be weak, be languid; be weak, limp, languid

via English Ness

StepLanguageWordMeaning
1EnglishNessAn Ulster princess and the mother of Conchobar mac Nessa and Findchoem in the Ulster Cycle of Irish mythology. Daughter of Eochaid Sálbuide. Also the mother of Cormac Cond Longas by incest with Conchobar mac Nessa
2Middle Englishnesse
3Old Englishnæsnot, not at all; not; first/third-person singular...
4Proto-Germanicnasjąfoothill; headland; cape
5Proto-Indo-Europeannéh₂snose
Every word from Proto-Indo-European slab-Every word from Proto-Germanic slēpanąEvery word from Proto-West Germanic slāpan