be in a coma沉迷不醒；不省人事。
coma n.昏迷(a state in which a person is unconscious and cannot be woken, caused by damage to the brain after an accident or illness)。coma stage昏迷期。

【例句】
A person can be in a coma for many months before waking up.
一个人可以昏迷数月才醒过来。

The patient rallied from the coma.
病人从昏迷中苏醒过来。