(I think I have all five)
Insomnia has many faces
With the help of thousands of volunteers, Drs. Tessa Blanken and her colleagues at the Netherlands Institute for Neuroscience now revealed why it has been so difficult to find consistent brain mechanisms and treatment effects. “While we have always considered insomnia to be one disorder, it actually represents five different disorders. Underlying brain mechanisms may be very different. For comparison: progress in our understanding of dementia was propelled once we realized that there are different kinds, such as Alzheimer-, vascular-, and frontal-temporal dementia.”
Five insomnia types
Surprisingly, the five insomnia types did not differ at all on sleep complaints like difficulty falling asleep versus early morning awakening. Some earlier attempts to define subtypes focused on these sleep complaints, and may therefore have been unsuccessful. Blanken and colleagues identified subtypes by looking beyond sleep complaints. They assessed dozens of questionnaires on personality traits that are known to be rooted in brain structure and function. Insomnia subtypes could be discovered by looking at trait profiles. Type 1 scores high on many distressing traits such as neuroticism and feeling down or tense. Types 2 and 3 experienced less distress and were distinguished by their high versus low sensitivity to reward. Type 4 and 5 experienced even less distress and differed by the way their sleep responded to stressful life events. These induced severe and long-lasting insomnia in type 4, while the sleep of type 5 was unaffected by these events .