Impact of circadian misalignment on energy metabolism during simulated nightshift work

Andrew W. McHill, Edward L. Melanson, Janine Higgins, Elizabeth Connick, Thomas M. Moehlman, Ellen R. Stothard, Kenneth P. Wright

Research output: Contribution to journalArticlepeer-review

241 Scopus citations


Eating at a time when the internal circadian clock promotes sleep is a novel risk factor for weight gain and obesity, yet little is known about mechanisms by which circadian misalignment leads to metabolic dysregulation in humans. We studied 14 adults in a 6-d inpatient simulated shiftwork protocol and quantified changes in energy expenditure, macronutrient utilization, appetitive hormones, sleep, and circadian phase during day versus nightshift work. We found that total daily energy expenditure increased by ?4% on the transition day to the first nightshift, which consisted of an afternoon nap and extended wakefulness, whereas total daily energy expenditure decreased by ?3% on each of the second and third nightshift days, which consisted of daytime sleep followed by afternoon and nighttime wakefulness. Contrary to expectations, energy expenditure decreased by ?12-16% during scheduled daytime sleep opportunities despite disturbed sleep. The thermic effect of feeding also decreased in response to a late dinner on the first nightshift. Total daily fat utilization increased on the first and second nightshift days, contrary to expectations, and carbohydrate and protein utilization were reduced on the second nightshift day. Ratings of hunger were decreased during nightshift days despite decreases in 24-h levels of the satiety hormones leptin and peptide-YY. Findings suggest that reduced total daily energy expenditure during nightshift schedules and reduced energy expenditure in response to dinner represent contributing mechanisms by which humans working and eating during the biological night, when the circadian clock is promoting sleep, may increase the risk of weight gain and obesity.

Original languageEnglish (US)
Pages (from-to)17302-17307
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number48
StatePublished - Dec 2 2014
Externally publishedYes


  • Appetite
  • Diet-induced thermogenesis |
  • Eating at night |
  • Insufficient sleep |
  • Melatonin |

ASJC Scopus subject areas

  • General


Dive into the research topics of 'Impact of circadian misalignment on energy metabolism during simulated nightshift work'. Together they form a unique fingerprint.

Cite this