If something is sobering, it stops you being light and cheerful and makes you go quiet and think seriously. A number, a piece of news, a photograph, a visit to a hospital — anything that suddenly shows you how real or how bad a thing is. The key is the change. 'Sad' just describes a feeling. 'Sobering' describes what a thing DOES to you: you were joking a minute ago, and now you are not. Common partners are 'a sobering thought', 'a sobering reminder', 'sobering statistics', 'a sobering experience'. You can also say 'It was sobering to see how little they had.' The picture underneath is drunk and not-drunk. 'Sober' first means having drunk no alcohol, and 'to sober up' is what happens to a drunk person as the alcohol wears off and they come back to the real world — slower, quieter, clearer. A sobering fact does that to your mind without any alcohol involved. Knowing that picture makes the word easy to feel. It is not a dark or dramatic word. It is calm. Bad news can make you cry; sobering news makes you sit still. Writers and journalists use it a lot, and it is very useful in a discussion or an essay when you want to say 'this made me stop and think' in one adjective.

令人警醒的、發人深省的、讓人笑不出來的。中文常說「這個數字很嚇人／讓人笑不出來」「一則發人深省的消息」。注意不是「悲傷的」，而是「讓你從輕鬆狀態安靜下來、開始正視現實」。