Poor posture creates fatigue by causing muscles, ligaments, and joints to work harder than they do when your body is aligned correctly.

Experts estimate that looking down at a 45-degree angle uses five times more energy than holding your head in an upright position. The added strain on muscles also decreases blood (and oxygen) flow to your brain by as much as 30 percent, making you feel tired.

To check your posture, draw an imaginary line from the middle of your ear through the centre of your shoulder and hip. Or have someone take a photo of you from the side – bad posture is easy to spot.

Correct your slouch by strengthening back muscles. Try two sets of 20 shoulder rolls forward and backward twice a week.