title: Breast cancer patients have progressively impaired sleep-wake activity rhythms during chemotherapy.
abstract: OBJECTIVE
  Prior cross-sectional studies have shown that cancer patients have sleep-wake activity cycles that show little distinction between daytime and nighttime, a pattern indicative of circadian disruption. This pattern is seen both before and during cancer treatment. Long-term data are needed, however, to assess to what extent circadian rhythm impairments evolve over the course of chemotherapy. The goal of this study was to assess the longitudinal course of sleep-wake activity rhythms before and during chemotherapy for breast cancer.
  
  
  METHODS
  Ninety-five women scheduled to receive neoadjuvant or adjuvant anthracycline based chemotherapy for a stage I-III breast cancer participated. The participants wore a wrist actigraph for 72 consecutive hours at baseline (pre-chemotherapy), as well as during the weeks 1, 2 and 3 (W1, W2, W3) of cycle 1 and cycle 4 of chemotherapy. Sleep-wake circadian activity variables were computed based on actigraphic data.
  
  
  RESULTS
  Compared to baseline, with the exception of acrophase, all circadian rhythm variables examined, including amplitude, mesor, up-mesor, down-mesor, and rhythmicity were significantly impaired during the first week of both chemotherapy cycles. Although the circadian variables approached baseline values during W2 and W3 of cycle 1, most remained significantly more impaired during W2 and W3 of cycle 4.
  
  
  CONCLUSIONS
  These data suggest that the first administration of chemotherapy is associated with transient disruption of sleep-wake rhythm, while repeated administration of chemotherapy results in progressively worse and more enduring impairments in sleep-wake activity rhythms.
authors.affiliation: School of Psychology, Université Laval, Québec, Canada.
authors.forename: Josée
authors.initials: J
authors.lastname: Savard
authors.forename: Lianqi
authors.initials: L
authors.lastname: Liu
authors.forename: Loki
authors.initials: L
authors.lastname: Natarajan
authors.forename: Michelle B
authors.initials: MB
authors.lastname: Rissling
authors.forename: Ariel B
authors.initials: AB
authors.lastname: Neikrug
authors.forename: Feng
authors.initials: F
authors.lastname: He
authors.forename: Joel E
authors.initials: JE
authors.lastname: Dimsdale
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Mills
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Parker
authors.forename: Georgia Robins
authors.initials: GR
authors.lastname: Sadler
authors.forename: Sonia
authors.initials: S
authors.lastname: Ancoli-Israel
mesh_terms: D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000009:adverse effects* / Q000627:therapeutic use; D001943:Breast Neoplasms / Q000150:complications / Q000188:drug therapy*; D017024:Chemotherapy, Adjuvant / Q000009:adverse effects; D002940:Circadian Rhythm / Q000187:drug effects*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008875:Middle Aged; D020178:Sleep Disorders, Circadian Rhythm / Q000139:chemically induced*
chemical_list: D000970:Antineoplastic Agents