PILLAR 4 Sleep

‘There’s a strong association between sleep and weight,’ says Dr Chatterjee. If you don’t sleep enough, your hormones change, so you’re hungrier. And when you sleep well, it’s easier to make healthy choices.

1SLEEP IN THE DARK Buy an alarm clock and leave your smartphone downstairs. Install blackout blinds or extrathick curtains.

2EMBRACE MORNING LIGHT Spend at least 20 minutes outside (without sunglasses) every morning. In one study, people who received more morning light had a lower body mass index. CREATE A BEDTIME ROUTINE

3Wind down by not looking at your laptop, smartphone or tablet for 90 minutes before bed. Set an alarm and go to your bedroom around 9.30pm. Read next to a dim light until you’re ready to fall asleep.

4MANAGE YOUR RACING MIND Don’t have difficult conversations or check your bank balance before bed. Try relaxing activities such as meditation or breathing exercises.

5ENJOY YOUR CAFFEINE BEFORE NOON It’s a big sleep disruptor, so swap for herbal tea or sparkling water.

◆ The Four Pillar Plan: How To Relax, Eat, Move And Sleep Your Way To A Longer, Healthier Life by Dr Rangan Chatterjee (Penguin Life, £16.99) is out now