how to say “wake-up” in Hebrew
הַשְׁכָּמָה
To wake up early is לְהַשְׁכִּים 
listen and repeat, an active-causative verb of the root שׁ.כ.מ (sh.k.m).
listen and repeat, an active-causative verb of the root שׁ.כ.מ (sh.k.m).Here’s a Biblical example:
וַיַּּשְׁכֵּם אַבְרָהָם בַּבֹּקֶר וַיַּחֲבֹשׁ אֶת חֲמֹרוֹ…
And Abraham got up early in the morning and saddled his donkey…
(Genesis 22:3)
For example:
יָרַדְתִּי לַלּוֹבי וּבִקַּשְׁתִּי הַשְׁכָּמָה בְּשֵׁשׁ וָחֵצִי.
I went to the lobby and requested a six-thirty wake-up.
A wake-up call in the proverbial sense is קְרִיאַת הַשְׁכָּמָה listen and repeat – literally, a wake-up call.
listen and repeat – literally, a wake-up call.For example:
מוֹת הֶחָבֵר הָיָה קְרִיאַת הַשְׁכָּמָה לְכֻלָּם.
The death of their (the) friend was a wake-up call to all them.