I have never experienced cessation, but I have experienced something similar in a dream. Of what I remember, there were long stretches of what i can best describe as nothingness, nothing occuring with no sensory experience and no emobidment, with only sporadic thoughts such as: "isn't something missing?". There were a few normal dreams in between. One scenario repeated itself, and once this was realised the dream ended and there was more 'nothingness'. 
Was this cessation or something different? Can anyone shed some light on this? I have mainly a dzogchen background if that helps.
Many thanks

I often have meditative experiences in dreams, including insights, so I don't see why not. Coincidentally, I had a dream on Tathātā or thusness last night which seemed perceptive and motivating.

Probably was something closer to a momentary formless jhana... you might be interested in this: https://www.mctb.org/mctb2/table-of-contents/part-iii-the-samatha-jhanas/28-the-formless-realms/

Can't make a diagnosis, that's above my paygrade, but this may help you: (Daniel Ingram's) List of symptoms for ñana diagnosis .

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Cessation is not "experienced". It is the absence of experience, or more importantly, the experiencer.

Not sure about cessation but I've had a couple that I assumed was just experience of dreamless sleep. It feels a bit clearer/cleaner than some of the waking jhanas, no nimittas or anything just sort of black. When waking it takes a different path like falling in between the frames of a movie and has more visual texture so I guess they are different.