Insomnia is the most common of sleep disorders. Almost everyone will experience insomnia at some point in their lives. However for those that suffer from chronic insomnia, life can be difficult. In my years in the sleep unit, I have seen many cases of reported insomnia that actually sleep quite well. This is known as sleep state misperception, or paradoxical insomnia. This is not exclusive to patients with insomnia, across the population a person’s perception of their sleep time is often pretty poor. I note this from experience. However this misperception holds true (in the literature) in that patients with insomnia often report different sleep times, compared to what is measured with a sleep study.
Feige et al. recently published a study in the journal of sleep that looked at the arousal thresholds (amount of stimulus required to wake someone) and the perceived sleep state after being awoken, i.e. did they feel they were asleep or not beforehand. They did this for both REM (dream state) and non-REM (NREM). They used two groups of 27 patients, one group of insomnia sufferers, and the other were healthy controls. They had these patients sleep in the sleep unit for four consecutive nights and woke them from either REM or NREM three times on the third and fourth night.
What they found was interesting, in that those with insomnia did not have a lower arousal threshold. And if awoken from NREM sleep, both groups reported having been asleep prior to arousal and had a similar level of confidence in this. However when awoken from REM sleep, the group of insomnia patients reported having been awake far more than those of the healthy controls (16.7% to 2.6%), and we less confident in reporting having been asleep or dreaming.
This study may hold some insights on the impact of the different sleep states on the sleep state misperceptions often reported by patients with insomnia.
Reference:
Bernd Feige, Svetoslava Nanovska, Chiara Baglioni, Benedict Bier, Laura Cabrera, Sarah Diemers, Maximilian Quellmalz, Markus Siegel, Ireni Xeni, Andras Szentkiralyi, John-Peter Doerr, Dieter Riemann; Insomnia – perchance a dream? Results from a NREM/REM sleep awakening study in good sleepers and patients with insomnia, Sleep, , zsy032, https://doi.org/10.1093/sleep/zsy032
