title: Serum copper, zinc and high-sensitivity C-reactive protein in short and long sleep duration in ageing men.
abstract: BACKGROUND
  Serum levels of zinc and copper have been proposed to associate with sleep duration. Mechanisms, such as inflammatory processes, have been suggested to relate this association. However, earlier studies have been conducted in small sample sizes. Human studies investigating the suggested associations while controlling for potential confounding factors are lacking.
  
  
  METHODS
  Population-based data consisted of 2570 men (aged 42-60 years) from Eastern Finland. The participants reported an estimate of their sleep duration. The serum levels of zinc (S-Zn), copper (S-Cu) and high-sensitivity C-reactive protein (hs-CRP) were measured. Analysis of covariance was used for multivariate analyses.
  
  
  RESULTS
  S-Zn levels and Zn/Cu ratio were lowest in ≤6h sleep. S-Cu levels were highest in ≥10h sleep. Elevated levels (>3.0mmol/l) of hs-CRP were observed in ≤6h and ≥10h sleep. After adjustments for age, cumulative smoking history (pack-years), alcohol consumption (g/week), Human Population Laboratory depression scale scores, physical activity (kcal/day), cardiometabolic syndrome, and cardiovascular disease history, sleep duration was significantly associated with levels of both S-Cu and hs-CRP. The association with S-Cu remained statistically significant following further adjustment for hs-CRP in the same model.
  
  
  CONCLUSIONS
  Our data suggests an association between S-Cu and sleep duration in ageing men. Elevated inflammation (measured as serum hs-CRP) does not explain this relationship. Mechanisms underlying the relationship require further investigation, as S-Cu may contribute to sleep regulation through pro-oxidative processes and copper-dependent N-methyl-d-aspartate receptor activity.
authors: Institute of Public Health and Clinical Nutrition, University of Eastern Finland, P.O. Box 1627, 70211 Kuopio, Finland. Electronic address: maria.luojus@uef.fi.
authors: Maria K
authors: MK
authors: Luojus
authors: Institute of Clinical Medicine/Psychiatry, University of Eastern Finland, P.O. Box 1627, 70211 Kuopio, Finland; Department of Psychiatry, Kuopio University Hospital, P.O. Box 100, 70029 KYS, Finland. Electronic address: soili.lehto@uef.fi.
authors: Soili M
authors: SM
authors: Lehto
authors: Institute of Clinical Medicine/Psychiatry, University of Eastern Finland, P.O. Box 1627, 70211 Kuopio, Finland; Department of Psychiatry, Kuopio University Hospital, P.O. Box 100, 70029 KYS, Finland. Electronic address: tommi.tolmunen@kuh.fi.
authors: Tommi
authors: T
authors: Tolmunen
authors: Institute of Clinical Medicine/Psychiatry, University of Eastern Finland, P.O. Box 1627, 70211 Kuopio, Finland. Electronic address: apelomaa@gmail.com.
authors: Antti-Pekka
authors: AP
authors: Elomaa
authors: Institute of Public Health and Clinical Nutrition, University of Eastern Finland, P.O. Box 1627, 70211 Kuopio, Finland. Electronic address: jussi.kauhanen@uef.fi.
authors: Jussi
authors: J
authors: Kauhanen
mesh_terms: D000375:Aging / Q000502:physiology*; D002097:C-Reactive Protein / Q000378:metabolism*; D003300:Copper / Q000097:blood*; D006801:Humans; D008297:Male; D018977:Micronutrients / Q000378:metabolism; D008875:Middle Aged; D015999:Multivariate Analysis; D012890:Sleep / Q000502:physiology*; D013997:Time Factors; D015032:Zinc / Q000097:blood*
chemical_list: D018977:Micronutrients; D003300:Copper; D002097:C-Reactive Protein; D015032:Zinc
keywords: Copper; High-sensitivity C-reactive protein; Sleep; Zinc