There is no quick test that can determine insomnia. Instead, the diagnosis of clinical insomnia disorder is based on a set of clinical assessment and interviews. These center on three core features: 1) difficulties falling asleep, 2) difficulty staying asleep, or 3) waking up and not feeling refreshed by your sleep.  Furthermore, to receive the diagnosis, you often have to be experiencing these things at least three nights per week; and having these issues for three straight months.One meta-analysis looked at over twenty studies of people with insomnia or healthy sleep. It found far fewer differences in their sleep recordings than you would imagine. The insomnia patients did spend more time awake, and there were reductions in their deep non-REM and REM sleep. But none of the differences  explain the degree of suffering for those with insomnia. This mismatch can be illustrated by an extreme example. There is a rare variant or subtype of insomnia called sleep state misperception. It is characterized by a mismatch whereby the patient reports their sleep as very bad. But the sleep recordings show a different story. The recordings show that the patient has slept a full, normal night of sleep, but the patient will tell you that they felt as though they never slept a wink! Such patients used to be dismissed as having nothing wrong with them. Now, science and medicine no longer take this view, and instead, understand that there is a mismatch going on, that the patient has a misperception of their sleep, and they still require clinical consideration.So, that’s an overview of insomnia classification and diagnosis. Please note that Matt is not a medical doctor, and none of the content in this podcast should be considered medical advice in any way, shape, or form, nor prescriptive in any way.The good people at InsideTracker are one of the sponsors of this week's episode, and they are generously offering a special 25% off any one of their programs for anyone who uses the above link during the time window of this episode. InsideTracker is a personalized biometric platform that analyzes your blood and your DNA to better understand what's happening inside of you and offers suggestions regarding things that you can do to better try and adjust some of those numbers, optimize them, and, as a result, optimize you.Also sponsoring this week are those fine people at Athletic Greens, and they are generously offering 3 benefits for anyone who uses the above link for their first order: 1) a discount on your order; 2) a one-year free supply of vitamin D; 3) five free travel packs. Athletic Greens is a nutrition drink that combines a full complement of antioxidants, minerals and biotics, together with essential vitamins. Matt’s been using it for several years now, first because he’s serious about his health, and second, because Matt did his research on the science and ingredients in Athletic Greens and thinks scientific data that can be taken as ground truth.So, make your way over to InsideTracker and Athletic Greens to take advantage of these incredible deals. And, as always, if you have thoughts or feedback you’d like to share, please reach out to Matt on Instagram.