just after falling asleep; the moment one falls asleep
Refers to the shallow sleep stage right after dozing off, often used when someone is easily woken or disturbed.
I was woken up by a phone call just after I had fallen asleep.
It's said that you tend to dream easily just after falling asleep.
Standard kanji-kana mixed spelling.
Alternate kanji spelling using 端 for ばな.
Compound of 寝入り (falling asleep) + ばな (just after, from 端 meaning 'edge' or 'beginning').