still waters run deep-静水流深
具体用法看例句：
During a nightmare, heart rate increases by seven beats perminute on average, says Michael Schredl, a dream and sleepresearcher at the Central Institute of Mental Health in Germany.Otherwise the sleeper typically lies still in bed: during REM sleep,muscles are paralyzed, which keeps people from acting out theirdreams.
德国中央心理健康研究所的梦境与睡眠研究员Michael Schredl表示，做噩梦时，每分钟的心率平均增加七次。除此之外，睡觉的人通常会静静地躺在床上：在快速眼动睡眠期间，肌肉处于麻痹状态，这会防止人们在梦中有所行动。
摘自《科学美国人》202300805期-Should You Wake Someone from the Throes of a Nightmare?