Due to copyright issues, an electronic copy of the thesis must be ordered from the faculty. For the faculty to have time to process the order, the order must be received by the faculty at the latest 2 days before the public defence. Orders received later than 2 days before the defence will not be processed. After the public defence, please address any inquiries regarding the thesis to the candidate.
Trial Lecture – time and place
See Trial Lecture.
Adjudication committee
- First opponent: Professor Tiina Maria Ikäheimo, The Arctic University of Norway,
- Second opponent: Professor Harald Carlsen, Norwegian University of Life Sciences,
- Third member and chair of the evaluation committee: Professor Asim K. Duttaroy, University of Oslo
Chair of the Defence
Associate Professor Frode Norheim, University of Oslo
Principal Supervisor
Senior Researcher Fred Haugen, STAMI
Summary
The body’s response to cold and pain changes depending on the time of day. This doctoral research shows that people tolerate cold better at certain times, and that the body’s natural rhythm—its internal clock—affects both thermal regulation and pain sensitivity. These findings may help improve work schedules and health protection for those exposed to cold environments, especially shift workers.
In Norway and worldwide, millions of people work outside the usual 9-to-5 pattern. For workers in industries like seafood processing, healthcare, transport, and offshore oil and gas, cold is part of the daily routine. At the same time, shift work is known to disturb the body’s internal rhythm and increase the risk of sleep problems, obesity, and type 2 diabetes.
What has been less understood is how the timing of cold exposure affects the body. Does it feel worse at night? Is the body more vulnerable in the early morning hours? These were the key questions in this PhD project.
Through a combination of laboratory experiments on mice and field studies on seafood workers in Northern Norway, the research found that both cold tolerance and pain perception vary with the time of day. Both mice and factory workers showed that the body’s response to cold depends on the time of day. In mice, cold exposure at different times triggered varying biological responses, indicating that thermoregulation is influenced by the circadian rhythm. Similarly, seafood factory workers displayed differences in hormonal and thermal responses depending on whether they worked morning, evening, or night shifts, suggesting that cold tolerance and recovery vary across the day.
In short, cold isn’t just cold, it depends on when it happens. And that insight could help workplaces reduce risk and improve well-being for people who work under cold conditions at irregular hours.
Additional information
Contact the research support staff.