Different regions of the brain can be in different states at the same time. Some areas show sleep-like activity, while others show wakeful activity. Siclari conducted sleep studies in a laboratory setting to investigate how these regional differences in brain activity influence our experiences during sleep.
Sleepwalking and insomnia
She investigated two sleep disorders: insomnia and sleepwalking. In these conditions, people feel or act as if they are awake, even though key brain areas show signs of sleep.
In people with insomnia who feel awake at night, parts of the brain remain more active compared to when they feel asleep, especially the front region involved in thinking and self-reflection. According to Siclari, it is therefore not surprising that these individuals report experiencing more ongoing thoughts than other individuals when they feel awake at night. This pattern can also occur briefly in people who sleep well, but less frequently and in smaller parts of the brain.
The experiences of sleepwalkers vary greatly. Sometimes they act on automatic pilot with little awareness, other times they have vivid experiences. Whether they are conscious or not relates to how much of the brain shows wake-like activity during a sleepwalking episode. In short: what we experience during sleep depends on which parts of the brain are in sleep mode and which parts show more wake-like activity.
Experiences are biologically grounded
According to Siclari, her research helps explain why patients' experiences during sleep are biologically grounded. "For people with insomnia, understanding that their experiences reflect measurable brain activity may reduce stigma. This research also supports more treatments that target specific brain areas."
For sleepwalkers, the biological explanation of their experience has implications for their diagnosis, safety planning, and even legal cases where responsibility is disputed. The research could be used to inform treatments that target mental activity specifically in these patients, like behavioral interventions or targeted hypnosis.
Siclari will defend her dissertation on 2 March.