meaning: sleep, sleepy
不眠症 == fuminshou == (noun) sleeplessness, insomnia, wakefulness
Left radical is 'eye'
(目). Right radical
is 'people/populace' (民), which acts phonetically to express 'close'.
To 'close the eye' is to sleep.
suggests as a
mnemonic: ' Populace closes its eyes in sleep.'