Commentary for Middot 1:2
אִישׁ הַר הַבַּיִת הָיָה מְחַזֵּר עַל כָּל מִשְׁמָר וּמִשְׁמָר, וַאֲבוּקוֹת דּוֹלְקִין לְפָנָיו, וְכָל מִשְׁמָר שֶׁאֵינוֹ עוֹמֵד, אוֹמֵר לוֹ אִישׁ הַר הַבַּיִת, שָׁלוֹם עָלֶיךָ. נִכָּר שֶׁהוּא יָשֵׁן, חוֹבְטוֹ בְמַקְלוֹ. וּרְשׁוּת הָיָה לוֹ לִשְׂרֹף אֶת כְּסוּתוֹ. וְהֵם אוֹמְרִים, מַה קּוֹל בָּעֲזָרָה. קוֹל בֶּן לֵוִי לוֹקֶה וּבְגָדָיו נִשְׂרָפִין, שֶׁיָּשֵׁן לוֹ עַל מִשְׁמָרוֹ. רַבִּי אֱלִיעֶזֶר בֶּן יַעֲקֹב אוֹמֵר, פַּעַם אַחַת מָצְאוּ אֶת אֲחִי אִמָּא יָשֵׁן, וְשָׂרְפוּ אֶת כְּסוּתוֹ:
The man [who is in charge] of the Temple Mount would go around to each and every guard. In front of him there were lit torches and any guard who was not standing [on guard], the man of the Temple Mount would say to him [the sleeping guard] "Peace onto you." If it was apparent that he [the guard] was sleeping he would hit him with his stick. He even had permission to burn his [the sleeping guard's] clothes. [If that occurred] they [the people on the outsde] would say "What is that noise in the Temple Courtyard?" [They were told that] it is the voice of a Levi being beaten and whose clothes are being burned because he slept on guard duty. Rebbi Eliezer ben Yaakov says: "They once, found my mother's brother sleeping and they burned his cloak."
Bartenura on Mishnah Middot
English Explanation of Mishnah Middot
And he had permission to burn his clothes. And the others would say: What is the noise in the courtyard? It is the cry of a Levite who is being beaten and whose clothes are being burned, because he was asleep at his watch. Rabbi Eliezer ben Jacob said: once they found my mother's brother asleep, and they burnt his clothes.
Today’s mishnah describes the officer in charge of security on the Temple Mount who would go around and check to make sure no one was asleep on his watch. If he found anyone asleep he would beat them, and perhaps even burn their clothes. Don’t ask me what they would do without any clothes!
The mishnah is straightforward (although a bit harsh) and therefore doesn’t really need explanation.