Get slim while you sleep

We as humans think we know it all, we've almost  unravelled the secrets of the Higgs Boson particle, we've explored every inch of the world and we've even landed a man on the moon. But there are many things we don't know, and I honestly love that. I love the idea that there are an infinite number of discoveries left to be made, most of which will not happen in our lifetime.

One of the forefront runners in the race of 'things we don't know' is why we sleep. The truth is I don't know and as far as I'm aware nor does anyone else. We spend a third of our lives in this blissful state of relaxation and all we know is this:



Sleep is vital to life

There has been a huge amount of research into the effects of acute sleep deprivation, both on animals and on humans. The more extreme studies on rodents has informed us that sleep as a vital function is right up there with food and water. If you withhold water rats will die in around 14 days, after 16 days they will die of sleep deprivation and after 18 days they will die of starvation.

'If sleep does not serve a vital function, then it is the biggest mistake the evolutionary process ever made' - Rechtschaffen

However in this modern world, sleep is given the back seat to other activities. Spending an extra half hour of time awake with a loved one while the children are asleep, or just quickly finishing the laundry or some other chore which you'd rather not leave until morning are classic examples of self sabotage. It is a reasonable thing to do, because if we don't know what the reason for sleep is, then why would be motivated to waste time in such an unproductive manner?

Below is a diagram representing self reported sleep statistics over the last 50 years.

 













Here's the issue; it is not wasted time. It's precious time to regenerate and recover from our daily grind. For example were you aware that people who slept less were more likely to put on weight?


In the 1930's we developed the ability to look at brainwaves and recognised that our brain didn't stop when we slept. We discovered that we all had three different levels of consciousness:

• Wakefullness
• REM sleep
• Non-REM sleep

We know that wakefulness is important for health as this is the time that we eat, drink, exercise and procreate, but there are two others which carry an equal weight. Without them we will die.

Assuming a healthy sleep pattern, we spend about six hours in N-REM sleep, this is important for feeling refreshed and our vitality. Within that we have our deep sleep which is linked to metabolic health.

We also have two hours REM sleep for cognitive health and wellbeing, this is where we dream and the thinking is that it helps to balance our emotions and keep is mentally healthy. But what are the essential mechanisms which are restored when we sleep?

It is common knowledge that eight uninterrupted hours of good sleep are necessary for functions to be carried out effectively and there are consequences to not getting enough sleep. This deficit does not necessarily come from not spending enough time in bed but also interruptions in the night; babies, toilet visits, noisy partners, early alarms etc.




There are both behavioural and physiological changes which result from sleep deprivation; both of which point in the direction of weight gain. The include poor mood and depression, lack of motivation , poor decision making and increased risk taking.

Physiological mechanisms for the connection between sleep and weight gain include the deregulation of our appetite hormones, neurocognitive changes and decreased energy expenditure

Leptin is a hormone which is produced by fat tissue to signal to the body that it has enough energy stored and that appetite needs to be reduced, so as not to increase weight too much. This is useful in controlling excessive weight gain, which in the wild would reduce the chances of you getting caught because you were rolling across the savannah.

A study published in 2004 examined the effect of different amounts of sleep deprivation on daily leptin levels in young males, ranging from 4hours per night to 9 hours per night.

What this study shows is that at 9am the level of Leptin is much lower in those who slept less. So those who sleep less or poorly have to eat much more food to feel satisfied.


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What's more (as the above diagram shows) ghrelin; the hormone which stimulates appetite, is increased when we sleep less. This potent combination means that someone who has had no sleep is both hungry and insatiable at the same time. As a result someone who has had 4 hours of sleep will on average consume 23% more calories per day than someone who is well rested.

Although appetite goes up 18%, appetite particularly increases for sweet foods. Can you really blame someone for wanting a bowl or sugary cereal downed with milk, orange juice and a sweet coffee first thing in the morning? Followed by biscuits at 11, coke and  chocolate bar at lunch etc...

There is of course the obvious answer, restraint. It's all good and well telling yourself not to eat the ice cream, or chocolate; but in practice you also have to burn extra energy to break even. This is because when you sleep less your resting metabolic rate decreases (see diagram below)

 

The outcome of all of this research is clear, that sleep is a vital function for maintaining a healthy body composition. To be honest I've only really scratched the surface on what is affected by sleep deprivation from a physiological perspective, I haven't discussed insulin resistance, irregular cortisol, adrenaline, inflammation and even performance. All these things are negatively affected by reduced sleep. The problem is that you can't sell sleep in a bottle, so no body ever really talks about it.

 

In my next article on sleep I will be covering advice on how to get better quality sleep.

 

Reference - http://sleepforhealth.net.au/sleepweight02.html