Sleep, somatic & dissociative overview

This topic bundles three families you only need to recognize, not master — but examiners love the one-line discriminators inside each. Learn the headline feature of every member and you're set.

Sleep — insomnia disorder. The prototype sleep-wake problem: dissatisfaction with sleep quantity or quality — difficulty falling asleep, staying asleep, or early-morning awakening — despite adequate opportunity, causing daytime distress/impairment. Think chronic, not the occasional bad night.

Somatic symptom & related disorders — the distinction is where the anxiety lands. Somatic symptom disorder (SSD) = one or more actual distressing physical symptoms plus excessive thoughts/feelings/behaviors about them (the symptom is real; the reaction is disproportionate). Illness anxiety disorder (IAD) = preoccupation with having/acquiring a serious illness when somatic symptoms are absent or minimal — the fear of being sick, not the symptom itself. Memory hook: SSD has the symptom; IAD has the fear.

Dissociative disorders — a disruption in consciousness, memory, identity, or perception. Three to recognize: Dissociative identity disorder (DID) — two or more distinct personality states plus recurrent gaps in memory (identity fragmentation). Dissociative amnesia — inability to recall important autobiographical information, usually of a traumatic/stressful nature, too extensive for ordinary forgetting (may include a fugue, purposeful travel/wandering). Depersonalization/derealization disorder — persistent/recurrent detachment from one's self (depersonalization) or surroundings (derealization), feeling unreal or robotic, with intact reality testing.

Clinical Pearl: The most-tested pair is SSD vs IAD — SSD = distressing real symptom(s) + excessive reaction; IAD = preoccupation/fear of illness with few or no symptoms. For dissociation, anchor on the definitions: DID = >=2 identities, amnesia = lost autobiographical memory, depersonalization/derealization = detachment from self/surroundings with reality testing intact.