Roaming at night, numb Somalis staggered miles (12)

I believe the answer is:

somnambulism

'roaming at night' is the definition.
(somnambulism is sleepwalking)

'numb somalis staggered miles' is the wordplay.
'staggered' indicates anagramming the letters.
'miles' becomes 'm' (common abbreviation).
'numb'+'somalis'='numbsomalis'
'numbsomalis' is an anagram of 'somnambulis'.
'somnambulis'+'m'='SOMNAMBULISM'

(Another definition for somnambulism that I've seen is " Sleepwalking".)

I've seen this clue in The Times.

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