In a recent thoughtful review of the potential relationships between sleep fragmentation and the clinical phenomenon of ‘dissociation’, van der Kloet and colleagues (Dalena van der Kloet, Harald Merckelbach, Timo Giesbrecht and Steven Jay Lynn; Fragmented Sleep, Fragmented Mind: The Role of Sleep in Dissociative Symptoms Perspectives on Psychological Science 2012 7: 159 DOI: 10.1177/1745691612437597) argued for the view that dissociative symptoms stem from disruptions in sleep states, most especially REM sleep. Dissociative symptoms refer to a range of non-ordinary experiences from “zoning out” to out of body experiences to outright distortions in the fundamental sense of self.
The authors argue that there are two broad types of dissociative experiences: those that issue from from a lapse in cognitive control (e.g., dissociative amnesia), and those that involve a kind of dissolution of the sense of Self (e.g., depersonalization, derealization, out-of-body experiences). Both types of dissociative experiences may, in turn be linked to an influx, from internal and external sources, of too much information. The cognitive system becomes overwhelmed with the amount of information. Memory systems cannot integrate the information so it floats around and issues into waking consciousness in disconnected fragments like false stories, false memories, illusions, delusions and finally false identities.
As the information overload escalates the self gets inundated and starts to buckle, which is of course extremely frightening for the individual. Nightmares may be experienced and then as these fail to get integrated into the system they too begin to emerge into waking life until mental breakdown occurs.
What causes the information overload in the first place? The fundamental cause may be due to failure of the mental system that normally integrates new information into existing information systems. That mental system that integrates new into existing information is sleep and dream dependent. So if the sleep and dream system is impaired so too will information processing systems be impaired and if they fail you will get information overload.
The sleep and dream systems can fail for a variety of reasons. Emotional trauma (like PTSD), stress, insomnia, physical illness, and a host of other issues can disrupt sleep. Disrupted sleep is associated with increased scores on dissociation inventories. Importantly, van der Kloet et al note that treating sleep deficits can lower scores on dissociation inventories.
What I want to ask is how precisely do dreams participate in this sleep-dissociation process? Dreams must contribute to the dissociation experience via their participation in the information integration process. But there are no precise or clear ideas as to how dreams participate in information processing routines. They very likely reflect memory consolidation processes as few REM dreams contain episodic memory references while many NREM dreams do.
Episodic memories may not occur in REM dreams because hippocampal outflow to the neocortex is blocked during REM. If the hippocampus contributes space-time tags or specificity to memory fragments this feature of information processing cannot happen during REM. Now if REM erupts into waking consciousness due to the multiple “microsleeps” commonly associated with sleep-deprived individuals, then those individuals are using decontextualized memory fragments to process incoming information and that could yield anomalous forms of information and unusual experiences. The individual would also have to play constant catch-up and try to develop reasons why his or her thoughts seem so fragmented. The individual would need to confabulate post hoc explanations for all these unusual experiences and so on. Those confabulations would be recorded as false memories by clinicians.
The good news is that if this story is at all correct we can treat the huge array of dissociative experiences, including those frightening instances where one’s sense of self is in danger of dissolution via treatment of sleep problems. We have to devise methods and pharmacologic treatments that can normalize sleep architecture and restore high quality sleep. Some effective treatments already exist. Simple sleep hygiene habits go a long way toward normalizing sleep patterns. Hopefully people will opt more often for high quality sleep than risk the dangers of sleep fragmentation.