The 24-hour clock always uses 4 digits. You see this most often on digital clocks. Complete this interactive activity to understand the 12 and 24-hour clock. Then put your knowledge to the test.

PA, SB and sleep are also linked to the 24-hour biological clock that regulates the sleep–wake cycle ... with a peer-reviewed journal. The label time-use (activity) behaviours—or the 24-hour activity ...

New research has uncovered how a simple circadian clock network demonstrates advanced noise-filtering capabilities, enhancing ...

The 24 Hours exhibition at Milan design week features 24 weird and wonderful clocks, all by different designers. We look at seven of the most imaginative examples. On show at Riviera, 24 Hours was ...