At ESPA/Luleå they have a single controller at work during the night, and he/she is allowed to sleep on a cot to the rear of the tower. (They are only there as standby for medical flights)
The way they do it, is that they set an alarm some time before the first mail plane is expected each morning. Now, a former instructor of mine is a rather heavy sleeper (apparently), and did not wake from the alarm one morning......and after a while Sundsvall ACC called with the inbound estimate for the mail C208. No reply. Tried all phonelines, and guard. Sleeping beaty did not wake up.
In the end (with the C208 in the hold) Sundsvall called the gate guards at the airforce base (ESPA is comb. mil/civ), and my former instructor woke to the sight of a conscript in combat gear shaking her awake!