We are all creatures of habit, even when we try to be spontaneous. True spontaneity is very difficult to keep up and we revert back to our humdrum regular behavior. Along with this habitual behavior comes our dependence on the clock. Even when we neglect to set the alarm, hoping, perhaps, that we may sleep in, we wake up as usual a few minutes before it is due to go off. Our circadian rhythms seem to take all our essential activities into account.

Mealtimes are just one of those essential activities and we start getting restive as they approach. Our animal friends also find themselves in the same boat. Once they get used to a set of mealtimes, they start to get excited as their internal clock warns them to get ready. Luby et al decided to use their mice to check out how they felt about regular feeding and published their data in PLoS ONE (1).

To start with, they put groups of their mice on a restricted calorie diet so there would be no eating between meals to spoil their appetites. Several regular feeding regimens were tried at 12, 8 and 4 hour intervals and the mice quickly got used to that and stamped about impatiently waiting for service.

18 hour feeding intervals were not well received as food would not arrive at a regular time each day and the mice could not fit lunch conveniently into their circadian rhythm. They did make an effort, but gave that idea a resounding raspberry.

A much more popular option was being fed once a day at a regular time, but with the meal split up into 6 small helpings served at 30 minute intervals, allowing plenty of time for socializing as a well brought up mouse may wish to do.

The net result was to show that mice were distinctly clockwise and therefore, creatures of habit governed by circadian clocks just like us. So if you want to catch your mice, try feeding them at regular times each day and avoid putting that trap out at odd times when you happen to think about it – they are much less likely to cooperate.


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