1. The Rhythm of the night: An examination of the role of the human circadian
system on decision making and motor performance
Nicholas Severson, Kelene Fercho, Lee A. Baugh
Basic Biomedical Sciences, University of South Dakota; Center for Brain and Behavior Research, University of South Dakota
This research was supported by the National Institute on
Drug Abuse (grant R25-DA033674)
● Previous research has found that our
circadian typology (night-owl, early-bird, or
neither) plays an influential role in several
major aspects of our lives (personality traits,
social relations, and health)
● Being out-of-sync with our circadian typology
(i.e. working overnights) has shown to
produce detrimental effects (short- and
long-term)
● Impulsiveness has been associated as being
characteristic of eveningness (night-owl or
ET), particularly when immediate rewards
are at stake; similar to a drug addict seeking
instant gratification.
● Desynchronization could be the root cause
of ETs inability to produce or sustain an
optimal level of self-control, that prevents
poor decision-making.
● Explore the relationship between chronotype,
neurophysiology, behavioral task
performance, and three types of impulsive
decision making—‘non-planning’, ‘motor’,
and ‘attentional’
● Hypothesized that time-of-day effects and
chronotype influence decision-making and
motor performance. Regardless of whether
trait impulsiveness is present in an individual,
desynchronization exacerbates
impulsiveness as a state
-Participants
● 24 morning-types and 24 evening-types,
based on morningness-eveningness
questionnaire (MEQ), from USD population
-Surveys
● Barratt Impulsivity Scale (BIS), Sleep
History Questionnaire, Brief Sensation
Seeking Scale (BSSS), Domain Specific
Risk Taking Scale (DOSPERT),
Self-Control Scale, and NASA TLX
--Behavioral protocol
● At two lab sessions (8 AM & 6 PM),
participants will partake in four tasks:
● Single outcome gambling - non planning
and financial impulsivity - 50:50 gambling
● Sustained Attention to Response Task -
attentional impulsivity - inhibiting response
when target number is displayed
● Go/no-go - motor impulsivity - inhibiting
response when non-targets are displayed
● Object manipulation - circadian rhythmic
effects on object interaction - block-lifting
with alternating sizes and weight
--Equipment
● Electroencephalogram (EEG) - measuring
event-related potential (ERP) of response to
sensory, cognitive, or motor activity
-Behavioral data
● Reaction times, selection frequencies, and
trends analyzed using repeated measures
mixed-model design analysis of variance
-EEG data
● Focus on delta (.5–3.5Hz) ,alpha
(7.5–12.5Hz), theta (4–7.5 Hz) and beta
(12.5–30 Hz) band differences.
● Low theta/beta ratio associated with higher
impulsivity
● Anticipated that participants will
demonstrate increased impulsivity in
out-of-phase testing sessions. Behavioral
and electrophysiological patterns are
expected to support our hypothesis that
desynchronization inhibits self-regulation
--Clinical and preventive applications
● Mental health practitioners may be
encouraged to adjust protocols that
support promotion of synchronization and
improved sleep behavior
● Prevention specialists can encourage
good sleep habits and identify those with
eveningness tendencies and self-control
issues, to prevent development of
addictive behavior
N Min. Max. Mean Std. Dev.
12 35 77 53.42 16.228
Previous Outcome Gain 50 Loss 50 Gain 10 Loss 10
Mean RT (ms) 411 385 408 377