Check the batteries in your carbon monoxide detectors.

There is no such device. What you need is, in all likelihood, a therapist, or a doctor in any case.

Choose from:

1. You have an undiagnosed medical issue that is making you feel something unusual when you lie down. Inner ear infection sounds possible.
2. You have an undiagnosed psychological issue that makes you think you are under attack when you are not.
3. You're correct and your neighbours are using something unknown to common science.

3 is unlikely to the point of impossibility. Anyone telling you different, perhaps in your DMs, will be seeking to manipulate you, or are also unwell themselves.

1 could be paired with 2, so there is a genuine feeling, but you are misidentifying its cause. Go see a doctor.

You absolutely need to see a doctor.

1. you have no proof you are perfectly sane. You may be experiencing some type of mental illness, you may even have a carbon monoxide leak (as in that very famous Reddit post), but in any case proof of sanity can really only be obtained through testing by a professional.
2. as the other reply states, there is no such device which can cause the symptoms you're feeling.

Be logical here, the most likely explanation is that your brain is not behaving for some reason.

First, I'm sorry you are in a dispute with your neighbors.

Second, it is unlikely, bordering on inconceivable, that the sensations you are experiencing are something your neighbor is physically doing to you. Physically, it's not possible to enact the forces required for the sensations you're describing without direct contact.

Please contact a doctor to discuss what you're experiencing: it could be an underlying medical condition.

Pretty much every response you get is going to be telling you to go and see a doctor, because that is the next logical thing to do. You don't need to tell them you think your neighbour is causing it, just that you're feelling this imbalance, and describe the symptoms.

There's a variety of things that could be causing these sensations, and you'll need to rule out the obvious ones first.

Vertigo could give you these sorts of sensations, and can be triggered or worsened by stress, which you're clearly feeling, as well as a variety of other medical issues, which your doctor should investigate. Things like an inner ear infection can be treated, but it could also be a symptom of something more serious, such as a mimor stroke or other damage.

Another aspect to check is your physical environment. Make sure you have a carbon monoxide alarm properly installed near any appliance that burns fuel, and also get your hone checked for gas leaks. Both can cause unpleasant effects, and both are very dangerous too. Get your electrics checked too, as something wrong there could also be causing an effect, like buzzing at a high frequency, the manifests itself in weird bodily sensations. Whilst you're at it, check your neighbourhood for any new industrial or manufacturing that might be releasing noxious fumes. Walk around and smell for any gas leaks outdoors too, just in case.

If you've ruled out physical health concerns and environmental issues, the most probable cause is psycological. To be clear, this doesn't make the symptoms any less real, or suggest you're just imagining them. Stress, and it clear that you are very stressed by the situation with your neighbours, can manifest in a variety of unpleasant ways, including the sorts of symptoms you've described, and worse. Talking to a mental health professional would be a good step to helping you deal with all of this, even if it's not a reaction to the stress of the unplesant situation you find yourself in with your neighbours.

Whatever the cause, I hope you manage to resolve it.

Time for a trip to the doctor's office. There is no such way to attack someone.

It's worded as "somehow" in your post because of how impossible it is.

I think this is my favourite April fools post so far

These feelings are not normal. Your neighbour can't be responsible. Seek psychiatric help.

Symptoms are similar to vertigo. Do you have any new stresses or medications lately? Ask a doctor to rule that out - it could be a sign of a larger health problem and you want to rule that out before you can start considering external causes.

This sounds like classic carbon monoxide poisoning. Get a gas detector. It could be that your upstairs neighbor is pumping it into your apartment! (more than likely though its juts a leak making you disoriented and paranoid).

Have you tried sleeping in somewhere else, like a couch in a different room? It could the the bed/pillow itself that makes it really hard to sleep. External sounds could also disturb your sleep too, maybe try some earplugs before sleeping? My sleep schedule got fucked around the times a construction started near where i live and i couldnt sleep properly until I started using earplugs, though other comments suggest an possible ear infection, so I'd highly suggest you to consult a doctor before doing so

In an hypothesis where your neighbor could cause shake your walls by leaning side to side, the apartment itself would be way too weak and it wouldn't pass any building inspection before being sold in the first place.