Nothing says "everything is fine, sleep well" quite like a few tinkling notes in a minor key. Play these ones for a friend and watch their spine try to leave the room without them - this is the theme from The Exorcist, and it has been ruining bedtimes since 1973.
In this short clip I take Mike Oldfield's Tubular Bells riff - yes, that Tubular Bells - and put it on the guitar. It sounds simple, and it mostly is, right up until you notice the beats don't add up the way your foot expects them to.
How the Exorcist riff quietly cheats on the beat
The reason this riff feels uneasy isn't just the notes - it's the meter. Oldfield wrote the opening in 7/8, which means every bar is one eighth-note shorter than the comfortable 4/4 your body is begging for. So the loop keeps arriving a hair "too early," and your ear never quite settles. On top of that it sits squarely in A minor, arpeggiating the notes of the chord one at a time instead of strumming them - so it rings like a music box that has seen things.
The useful takeaway: count the phrase out loud as "1-2-3-4, 1-2-3" instead of trying to feel it as one lump. Group the seven eighth-notes into a 4 and a 3, tap your foot only on those two downbeats, and let your picking hand roll through the arpeggio underneath. Do that and the spookiness becomes a feature you control, not an accident. If you want to go deeper on odd meters, my breakdowns of time signatures and the 7/8 in Solsbury Hill use the exact same counting trick.
Warning: learn this properly and you will play it at every single family gathering until someone hides your guitar. Grab the PDF, Guitar Pro file and the full video over on my Patreon, and may your neighbours sleep with one eye open.