It’s ironic that just as I’m writing ‘Habit 30’ of my new book – a habit I’ve called ‘Sleeping your way to the top’, I’m feeling the effects of a very bad night’s sleep. Maybe it’s the excitement of being so close to finishing the book (the title of which I’m still umming and aahing about!) and finally nailing the 31 habits I’ve spent so much time writing about in between other commitments. The thing I’m noticing most is just how hungry I am. I feel as if I haven’t stopped eating all day long.

As it turns out there is a very good explanation for this, and it’s to do with sleep and the hormones that depend on it.

More of this in a moment but first let me say this: if you have ever struggled to lose weight, or feel that you’re doing all the right things food-wise but still not reaching your full wellness potential, then this could hold your answer. And yet the power of sleep is incredibly undervalued.

Why is this a big mistake?

If at first sight, sleep seems like nothing more than unproductive downtime, it is in fact essential maintenance and repair time for your body and brain. You’ve seen the state of buildings from the 60’s which have been neglected… everything starts to peel away, decay and go wrong! And then there’s the price you pay for ignoring the circadian rhythm.

So why is the circadian rhythm so important?

All of the hormones which regulate our metabolism are orchestrated around a 24 hour cycle based on the perception of light by our retina.

Because humans (unlike most other mammals) sleep in a single period of 7-9 hours, we need to maintain our glucose balance in spite of a long period of fasting during the night. This is why our physiology works very differently depending on whether we’re in the wake state or the sleep state.

And the reason why we are so susceptible to disturbances in our rhythm, such as jet lag, shift work, or blue light in the evening. It’s hardly surprising therefore that studies consistently show an increased risk for type 2 diabetes for shift workers for instance.

Sleep, hormones and food

Have you ever noticed that you can’t stop eating after a bad night’s sleep? That’s because poor sleep disrupts the hormones that regulate our appetite:

  • It increases ghrelin, which you can blame for making you feel hungry even when your body has enough food (yes it’s not just your imagination!)
  • It decreases the chemicals serotonin and dopamine, making you crave sugary foods. And it’s not just how you feel about food that’s being affected by poor sleep, it’s what your body does with it too:
  • It decreases growth hormone, making it harder to burn fat and lay down lean muscle.
  • It can directly affect the way our body handles glucose (whether it gets used as energy or stored as fat).  Just one night of partial sleep restriction is enough to blunt our cells’ insulin sensitivity the following day.
  • And finally it increases cortisol, “the stress hormone”, leading to the breakdown of muscle, increasing blood sugar and insulin (hence deposition of fat, mainly around your waist.)

Steps you can take for using the power of sleep to your advantage

Research shows that we mostly need at least 7 hours of good quality sleep, so what steps can you take if you haven’t quite cracked it yet? There are three areas you can focus on:

Timing and preparation

  • Aim to get to bed around the same time each night, ideally around 10 PM (or if that’s a bit of leap, start by bringing bedtime forward by half an hour).
  • Design your bedroom primarily to support good sleep. Keep it clean and uncluttered
  • Listen to white noise or relaxation CDs
  • Make sure you are exercising regularly.

Eating and drinking

  • Avoid snacking on sweet or starchy foods just before bedtime as they raise your blood sugar and inhibit sleep (or wake you up when your blood sugars drop!)
  • For the same reason avoid or limit alcohol (ever woken up in the middle of the night after a few glasses too many?)
  • If you do snack before bedtime, choose protein. It won’t disturb your blood sugars as much and will provide L-tryptophan, a precursor to melatonin and serotonin
  • Avoid caffeine as much as possible


  • Avoid screens (TV, smartphones and computers) for at least an hour before the time you’d like to sleep
  • Keep the lights down in the evening and don’t turn them on if you have to get up during the night as bright light will affect your circadian rhythm.

Sweet dreams…