The Effects of Chronic Partial Sleep Deprivation and Circadian Rhythms on Semantic Memory and General Arousal

Open Access
Author:
Derise, Philip Angelo
Area of Honors:
Psychology
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Frederick Martin Brown, Thesis Supervisor
  • Kenneth Levy, Honors Advisor
Keywords:
  • chronic partial sleep deprivation
  • circadian rhythms
  • semantic memory
  • general arousal
  • immediate serial recall
Abstract:
Sleep deprivation is a rampant phenomenon that affects millions of people around the world. Acute or total sleep deprivation (TSD) refers to the “elimination of sleep for a period of time (at least one night),” whereas chronic partial sleep deprivation (PSD) refers to persistent “... reduction in sleep time below an individual’s usual baseline” (Reynolds & Banks, 2010, p. 91). Chronic PSD occurs far more frequently than TSD, and constitutes a growing public health epidemic (U.S. Centers for Disease Control and Prevention, 2014). Semantic memory refers to our conceptual knowledge about the world, including people, objects, facts, relations, rules, ideas, and beliefs (Saumier & Chertkow, 2002). Past studies have found that TSD leads to impaired semantic memory (Harrison & Horne, 1997; Harrison & Horne, 1998; Tilley, Horne, & Allison, 1985). We extended this research, by investigating the effects of chronic PSD and circadian rhythms on semantic memory. Twenty-three participants (8 males, 15 females, mean age 19 years) who were either chronic PSD (n = 10) or well-rested (n = 13) performed an immediate serial recall (ISR) task involving three word classes that differed according to their semantic representations: concrete content words, abstract content words, and function words. We observed a previously undocumented pattern of semantic impairment in the chronic PSD group, such that function words were the most frequently impaired word class. Additionally, there were significant performance differences on the Psychomotor Vigilance Task (PVT), Mood Scale II, and Stanford Sleepiness Scale (SSS) averaged across the chronic PSD and well-rested groups at two different test sessions 12 hours apart. These findings suggest that the assessment of semantic memory is relevant in the evaluation of individuals suspected of being chronic PSD. Furthermore, they suggest that the systematically cycling rhythms of circadian arousal affect alertness and peak performance at different times of the day. Future research requires data from a more representative sample, as well as the use of actigraphy to confirm participants’ self-reported measures of sleep duration.