Refers to the act of waking from sleep, often with a nuance of the state or feeling upon waking. Commonly used in expressions like 寝覚めが悪い (waking up feeling bad/unrefreshed) or 寝覚めの悪い思い (a guilty conscience that disturbs one's sleep).
I woke up feeling unrefreshed this morning.
His words left me with a guilty conscience that kept me awake.
ninth lunar month
uneasy conscience; guilty feeling
Compound of 寝 (ne, 'sleep') and 覚め (zame, the rendaku form of 覚め same, 'waking'). The exact historical derivation is uncertain, but the word has been used since classical Japanese.