Is statistical learning affected by sleep apnea?

It is thought that sleep is important for learning yet we know strikingly little about the relationship between sleep and a form of implicit learning known as statistical learning (SL). SL can be assessed using a distinct familiarisation phase in which participants are exposed to a stream of stimuli that contains statistical regularities but are not given any instruction to learn or any form of reinforcement. This is followed by a surprise test phase some time later where implicit learning of those statistical regularities is assessed. In the current study we investigated the relationship between sleep and SL across a period that included night time sleep with polysomnography (PSG) monitoring. Participants were 47 adults (mean age = 48.79 years, sd = 8.76 years) known to have impaired sleep due to obstructive sleep apnea. They were exposed to familiarisation in the evening prior to going to sleep and undertook the surprise test phase the following evening, approximately 24 hours later (mean overnight sleep time = 399.60 mins). Results revealed that, as a group, participants showed statistically significant SL despite the substantial delay between familiarisation and test phases. Although we found no relationship between individual differences in SL and clinical measures of sleep apnea severity, our findings revealed that SL is positively correlated with non rapid eye movement sleep (NREM).