Sleepwalking (SOMNAMBULISM)

Sleepwalking (SOMNAMBULISM)

1. waking and sleeping occur at the same time. Most episodes are short and last from a few seconds to minutes.

2. GENETIC EXPLANATION

   • Research has shown a concordance between somnambulism and genetic similarity
   • continuity for somnambulism - high proportion of adults sleepwalking have history of it as children
   • BAKWIN - 19 MZ twins and 14 DZ twins. Concordance of 47% for MZ and 7% for DZ. More siblings of MZ somnambulists walked in their sleep compared to what would be expected in general pop.
     • HUBLIN - 1045 MZ and 1899 DZ twins. Used questionnaires and interviews to assess frequency of sleepwalking through their lives. Greater concordance amongst MZ. Also found continuity for sleepwalking. 89% of males and 85% of females had history as children
       • Methodological Issues - twin studies. Mz more similar. Not 100% concordance

3. NEURAL EXPLANATION

   • Occurs as a result of environmental factors such as consumption of drugs and alcohol, which disrupt neural functioning
   • The temporal lobes which house the amygdala and hippocampus are involved in: auditory perception, memory, speech, emotional response and visual perception.
     • temporal lobes more active during sleep in sleep walkers and that GABA levels are reduced in the sufferers brain.
     • GABA is normally in low levels in the motor cortex when waking to permit planning, co-ordination and execution of movement. During sleep there is an elevation of GABA to inhibit activity in the motor cortex so we can't move around.
       • Sleepwalkers have low levels of GABA in the motor cortex whilst sleeping. Sleepwalking is more common among children, who have an under-developed GABA system (OLIVIERO)
   • ATAY & KAREAN - studied 22 somnambulists and found abnormal temporal lobe activity in 12 of them. In 11 of the 12, somnambulism stopped after taking anti-convulsive meds, suggesting caused by abnormal activity in temporal lobes.
     • Methodological issues - small samples, not representative of whole population of sleepwalkers. hard to generalise may not all be caused by abnormalities in temporal lobes.

4. REDUCTIONIST - other environmental factors: stress, alcohol, sleep deprivation can often induce sleep. Medical conditions like fever, night time asthma and panic disorders are linked with increased sleepwalking.