Thank you for your advice! I’ll try to make a promenade in my apartment to get tired. Maybe it’s the lack of physical activity.
Then you need this:

I think I’ve found a solution. I’ve successfully (and unusually) tested it today, it worked.
I’ve listened to the voice of a very famous italian anchorwoman, Maria De Filippi, who presents a sort of heartbreaking reality show.
I don’t usually watch that show, but today, by chance, I stumbled into a recorded episode and watched it.
The flat and croacking tone of her voice induced me to close my eyelids, and in no time I was sleeping!
When I woke up the video was ended. I slept for about 30 minutes.
Well, for those who don’t know who Maria De Filippi is, here is a full episode of her show, “c’è posta per te” (“there is a mail for you”):
Please tell me, what do you think about her peculiar voice? 
Was she a guest on Stasera Casa Mika?
Hmm, I checked, but Maria De Filippi was never a guest in Stasera CasaMika.
When I watched that show there was a woman on there who sounded similar. Maybe it’s just Italian sounding. 
Maybe was Maria Concetta Mattei. Here’s the episode:
Amusing, but no. 
Hmm, interesting. Thanks for sharing!