I mentioned this in another thread, but I have two very distinct types of tinnitus. One is the "normal" continual tinnitus related to my hearing loss, which is the ringing/buzzing/whining/etc noise that one normally thinks of when thinking about tinnitus. I've had that all my life and it has nothing to do with M.E. My understanding is that this kind of tinnitus can be exacerbated by stress, and it's also more noticeable in quiet situations (e.g. when you're trying to sleep!). The sounds can be simple or very complex, often have directionality, and are very clearly just sounds, or perceptions of sounds. The other type I have is very strongly correlated with M.E. symptom severity, is unilateral, lasts only a few seconds at a time (although it can happen multiple times in a day), only occurs when I'm in an upright sitting or standing position, and involves a physical pulsing sensation as well as a ringing sound. The pulsing is much faster than my heartbeat, so I'm pretty sure it's not pulsatile tinnitus. Interestingly, I can contract my tensor tympani muscles at will, which produces a rumbling sound and a physical pulsing sensation in my head. The pulsing sensation feels a lot like this second kind of tinnitus (although the sound is very different), which makes me wonder if there's some kind of muscle spasm going on as I enter PEM. Fasciculations and twitching aren't unknown in M.E. and perhaps in my case this tinnitus is just one more manifestation of that. Here's a paper on BMC about people who can deliberately contract their tensor tympani. You'll notice they mention that it stops you being able to hear properly: https://journalotohns.biomedcentral.com/articles/10.1186/s40463-016-0182-y Edited to add: This pulsing tinnitus has been really bad for me this past week (I've been quite unwell), and I no longer think the tensor tympani thing could have anything to do with it. The pulsing sensation is roughly in the area of the paretial bone on the right hand side of my cranium. It's a distinctly different place to a spasm in my TT muscles.