CBT-I Improves Sleep Pressure as Measured by Stage 2 sleep K-complexes

K-complexes are a distinct brain wave pattern in Stage 2 sleep that indicate the brain is losing awareness of the external environment as it descends into deep sleep and dream sleep.  A new study examined the relationship between K-complexes (KC) and CBT-I in which KC were used as a measure of sleep pressure that increases with prior wakefulness and adenosine accumulation. The study also examined whether KC can predict treatment response to CBT-I.

A sample of just under 100 individuals with insomnia underwent a 6–8 week in-person CBT-I program, with pre-and post-treatment evaluation of insomnia conducted using polysomnography (EEG) and the Insomnia Severity Index (ISI). The main outcome was the density of KC in Stage 2 sleep (number of KC/minute). The insomnia sample was also categorized into Responders (ISI decrease ≥8) and non-Responders (ISI decrease <8).

The results indicated that KC predicted treatment response to CBT-I (the greater the improvement in sleep, the greater the increased density of KC) and served as a marker of improvement in sleep pressure. These findings suggest that CBT-I increases sleep pressure in patients with chronic insomnia as measured by KC, and that KC are a novel and relevant EEG biomarker for insomnia.