Circadian Rhythm Disruption Effects on Smoke Inhalation
Condition: Inflammation; Sleep Deprivation; Circadian Rhythm Sleep Disorder, Shift Work Type; Smoke Inhalation
MeSH terms: Respiratory Aspiration; Sleep Wake Disorders; Sleep Deprivation; Sleep Disorders, Circadian Rhythm; Inflammation; Smoke Inhalation Injury
Study type: Interventional

Summary: 
      Particulate matter exposure during smoke inhalation provokes inflammatory immune responses in
      people exposed to burning biomass including fire fighters and civilians. Persistent
      occupational exposure to particulate matter represents a unique hazard for firefighters,
      underpinning a burgeoning research area. This trial will evaluate the effects of sleep
      deprivation and circadian rhythm disruption on the inflammatory response to woodsmoke
      associated particulate matter exposure. Participants will undergo 2 experimental trials in a
      randomized cross-over design. Participants will have either an 8-hour sleep opportunity or a
      4-hour sleep opportunity prior to reporting to lab for a 45 minute simulated firefighting
      trial (wood smoke associated particulate matter filtered to 2.5 um at a concentration of 250
      ug/m^3, while exercising at a moderate intensity). The effects of sleep restriction and
      simulated firefighting will be measured.
    

Detailed description: 
      Participants: Healthy college age males (n = 15), free from disordered sleep and without
      recent trans-meridian travel (within the last 2 weeks) will be recruited for this study.
      Participants will complete chronotype questionnaires (Morningness-Eveningness Questionnaire;
      MEQ, Munich Chronotype Questionnaire; MCTQ) to establish intermediate chronotypes. This will
      minimize the effect of circadian preference on the morning exposure to smoke. Participants
      will subsequently be outfitted with activity monitors (ActiCal) to monitor sleep and physical
      activity throughout the experimental duration. Participants will be asked to maintain a
      normal sleep schedule for at least 3 days leading up to the experimental trials and keep a
      sleep log to verify.

      Experimental Trials: Participants will undergo 2 experimental trials in a randomized
      cross-over design, with at least 1 week washout period between trials; 1) NS-250: Normal
      Sleep with exposure to woodsmoke at 250 µg/m^3, and RS-250: Restricted Sleep with exposure to
      woodsmoke at 250 µg/m^3. Participants will have an 8-hour sleep opportunity in their own home
      during the NS trials (22:00-06:00), and a 4-hour sleep opportunity during the RS trials
      (00:00-04:00). In all trials, participants will report to the laboratory at 07:30 the morning
      after the experimental sleep night. PM exposure will occur from 08:00-08:45 while cycling at
      70% heart rate reserve (HRR) to simulate the physical demands of firefighting.

      Exhaled Breath Condensate (EBC): EBC will be collected using standardized 10 minute
      collection techniques. In order to preserve sample integrity for potentially labile
      biomarkers (e.g., oxidative stress), sample pH will be measured immediately prior to
      aliquoting in multiple cryotubes (500-700µl), flash freezing, and storage at -80 degrees C
      until further assay. Standardized biomarker panels for oxidative stress and inflammation will
      be performed using a single thaw approach.

      Inflammatory biomarker analysis: Blood will be collected into heparinized vacutainers before
      (PRE) and immediately following (POST) PM2.5 exposure and spun down for plasma collection.
      Plasma will be assayed for inflammatory biomarkers (interleukin (IL)-6, tumor necrosis factor
      (TNF)-α, pentraxin-3, and C-reactive protein (CRP)) using standard enzyme linked
      immunosorbent assays (ELISA).

      Circadian Rhythm Assessment: Throughout the experimental protocol, circadian rhythms will be
      assessed in two ways; 1) Actigraphy and 2) Clock gene expression in buccal cell swabs.
      Acticals will be worn throughout to gather sleep variables (timing, duration, quality). Clock
      gene expression (CLOCK, BMAL1, PER2) will be measured in swabs taken from the cheek at 6 hour
      intervals (00:00, 06:00, 12:00, 18:00) to assess the effects of sleep deprivation on the
      molecular circadian rhythm. Cheek swabs will be immediately placed in RNA stabilization
      buffer until isolation. Swabs taken at 00:00 will be performed with minimal exposure to light
      to avoid disruption of sleep. These methods have been used previously to assess normal and
      disrupted sleep.
    

Intervention name(s): Sleep Restriction; Normal Sleep
Intervention type(s): Behavioral; Behavioral
Intervention description(s): Participants will be allowed ~4 hour sleep opportunity during the restricted night of sleep prior to reporting to lab for a simulated firefighting session.; Participants will be allowed ~8 hour sleep opportunity the night of sleep prior to reporting to lab for a simulated firefighting session.
Other intervention name(s): Circadian Rhythm Disruption; SR; NS
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: Randomized cross-over design
Masking: None (Open Label)
Primary purpose: Basic Science