如果你突然有点困，可以用英语说 "I suddenly feel tired/sleepy."

这个表达的来源是由 "suddenly" 和 "feel" 这两个动词组成。"Suddenly" 意思是突然地，"feel" 意思是感觉，所以 "I suddenly feel tired" 就是指你突然感到疲劳。

其他一些英文例句及其中文翻译如下：

I suddenly felt a wave of nausea wash over me. 我突然感到一阵恶心。
She suddenly felt a sharp pain in her stomach. 她突然感到肚子里剧烈的疼痛。
He suddenly felt his knees give out and he collapsed to the ground. 他突然感到双膝软塌，倒在地上。