Learn Turkish: Nöbetteyken uyumak yasak. - Sleeping is forbidden while on guard duty.

The suffix -ken means "while." When you attach it to a word ending in a vowel, like nöbette (on duty), you must use the buffer letter -y- to connect them. So, nöbette + y + ken becomes nöbetteyken (while on duty).

Could I just say nöbetken instead of nöbetteyken?

No, because nöbet just means "guard duty" or "shift." To say "while on guard duty," you first need the locative suffix -te (at/on) to make nöbette. Then you add -yken to get "while on guard duty." Saying nöbetken would sound like "while being a guard duty," which doesn't make sense!

Why is the verb "to sleep" used in its dictionary form (uyumak)?

In Turkish, the infinitive form (-mak or -mek) acts like a noun. Here, uyumak acts as the subject of the sentence, meaning "sleeping" or "to sleep." The sentence essentially translates to "Sleeping is forbidden."

How does this sentence say "is forbidden" without an actual verb at the end?

In Turkish, sentences can end with a noun or an adjective, and the verb "to be" (am/is/are) is often just implied. Yasak means "forbidden." When placed at the end of a sentence stating a general rule, it perfectly expresses "is forbidden" without needing any extra suffixes.