Having the weight of the world on your shoulders is more than a figure of speech - it can describe a physical reality for some, according to psychologists.
New research shows that the more socially powerless a person feels, the heavier objects seem to be.
Scientists tested the theory by asking volunteers to lift boxes of varying weights and guess how heavy they were.
Those who felt they lacked control in their lives consistently perceived the boxes to be much heavier than did individuals with a keen sense of personal power.
"Although many psychological studies have been conducted on power, not much was known about how power influences actual perceptual experiences in everyday life," said lead scientist Eun Hee Lee, from Cambridge University.
"This research demonstrates that people's social role, as indicated by a sense of social power, or a lack thereof, can change the way they see the physical environment."
The over-estimation of weight may be a relic of our evolutionary past to help us cope with depleted resources, the team believes.
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In a position of powerlessness caused by famine or lack of shelter-building material, it would be advantageous to have an overly cautious approach to the world, say the researchers.
Experiencing physical attributes such as weight in an exaggerated fashion may be a symptom of this instinctive desire to conserve resources.
The findings appear in the latest edition of the Journal of Experimental Psychology.
Three separate studies were conducted, all disguised by cover stories so that participants were unaware of what was being tested.
In the first, 145 volunteers were asked to rank how strongly a series of statements applied to them, such as "I can get people to listen to what I say".
The responses provided a measure of how they viewed their own power in social relationships.
Next they were asked to guess the weight of a number of boxes before taking a final test to gauge their mood.
The findings showed that as feelings of social power fell, the guessed weights of the boxes increased.
In a further experiment 68 participants were asked to recall an experience in which they had felt either powerful or powerless, then repeatedly estimate the weights of various boxes.
They were told the study was looking at the effect of exercise on autobiographical memory.
Volunteers who focused on "powerful" incidents were more accurate at guessing the weights. In contrast, those recalling "powerless" situations continually overestimated the heaviness of the boxes.
Another test allowed the researchers to manipulate sense of power by asking 41 participants to sit in either an expansive, domineering, arms-spread position, or a more constricted one with hands tucked under thighs and shoulders dropped.
Again, feeling powerful was associated with greater accuracy. Volunteers taking up the "powerful" pose guessed the weight of the boxes correctly while those in the "submissive" pose imagined heavier weights.
Lee added: "Power plays a role when it is present in a given moment, but also when it comes to people's personality.
"We find that personality, which determines how people interact with the social world, also shapes how people interact with the physical world."