Over the thirty years of my ME I have experienced what seems like every possible variation of sleep disturbance from hypersomnia via sleep reversal to insomnia, but overall I don’t think there any simple linear relationship between severity of my ME and the amount of sleep I am able to get. I have had insomnia and/or disrupted sleep patterns when mild and also when severe. Generally I did find when I was recording my activity levels that disrupted sleep patterns are a feature of PEM, but generally at such time my total amounts of sleep were, though fragmented, a pretty constant six to eight hours a day, even if I mistakenly felt I was sleeping more. If I was objectively sleeping less for a day or so it was followed by a rebound of extra sleep over the next few days. Certainly over a week my sleep levels would average to the normal six to eight regardless of what time of day the sleep periods occurred.
My ME is of the relapsing and remitting form, though over time relapses have been worse and remissions involve less improvement, giving an overall trend of deterioration. For me subjectively, beyond the association of disrupted sleep patterns linked to PEM, the only time I have experienced a potential pattern is with hypersomnia or marked increased sleep over a twenty four hour period occurring when I believe there were marked deteriorations in my underlying ME. This was clearly the case initially following the original active EBV trigger for my ME and following the seasonal flue that triggered my first major relapse when I could be sleeping as much as twenty hours a day. Subjectively it has also been to a lesser extent associated with relapses associated with specific episodes of over exertion or relapses with a more gradual onset. However in these situations the increase in sleeping time was less marked and I have no evidence that this was definitely an objective phenomenon.
In summary - Though my sleep patterns can be very variable and PEM is associated with disrupted sleep patterns, at such times it can feel subjectively I am sleeping more. However when I have recorded it although sleep invades more of my day I am sleeping pretty much the normal totals over a several day period. At any one time the total amount of sleep I need does not seem to bear any simple linear relationship to the current severity of my ME.
In contrast I do believe that when a deterioration in my underlying condition is actively happening, then I do sleep more, for example sleeping as much as twenty hours a day following acute viral infections.