Sleep! I love it! I really really love it! I love it so much that in the morning when I’m making my bed I secretly say in my head (or sometimes out loud) “I’ll see you tonight dream lover, yes you with your soft memory foam topper and your luxurious Linen Sheets”.

Did you know that if you're sleeping less than 5hrs a night you are 200% - 300% more likely to catch a cold, or if you have been awake for 21hrs you are functioning the same as a person who is legally drunk, or that sleep is the greatest cure for our immune systems, or that less sleep does not equal more productivity in your life and the less you sleep the more you eat!

Whether you get a little or a lot, we all need sleep, and I had the honour of interviewing sleep guru Dr Matthew Walker and asked him WHY we need it.

Dr Matthew Walker is a Professor in Neuroscience and Psychology at Berkley UC. He co-founded the Centre for Human Sleep Science 20 years ago and is currently the director. He has published over 100 scientific studies and is the author of number one best sellers, ‘Why We Sleep’ and 'Unblocking the Power of Sleep and Dreams’.

I personally had a few questions I couldn't wait to ask the doctor. Enjoy!

- Emma Henderson (Co-founder of The Beach People)

What really happens to our bodies and immune systems while we are asleep?

Lot’s of amazing benefits happen when we sleep. We used to ask the question; what does sleep do? Why do we sleep? What is the function of sleep? Based on the past 30 years of evidence, we’ve actually had to reverse that question. We now ask "is there anything in the brain or the body that sleep does not beneficially enhance when you get it?" Or "is there anything that is not demonstrably impaired when you don’t get enough sleep?" And the answer is no!

Every single physiological system within the body, and every cognitive and emotional operation of the brain, all of them are enhanced by sleep when we get it and remarkably impaired when we don’t get enough. I’ll speak a little bit about the question regarding the body and I will just give you maybe 3 examples.

1. We know that if you were sleeping maybe just 5-6 hours a night for just one week, your blood sugar levels are disrupted so significantly that your doctor would classify you as being pre-diabetic.

2. We know that there are correlations between sleep and the immune system. If you are sleeping 5 hours a night you are 4 times more likely to catch a cold relative to someone who is sleeping 8 hours a night.

3. We know that if you take an individual and you limit them to just 4 hours of sleep for one single night, what we see is a 70% reduction in critical anti-cancer fighting immune cells that we call natural-killer cells.

So without enough sleep the metabolic system, the immune system and the cardiovascular system become impaired, and all it takes is just one hour of lost sleep.

There is a global experiment that is performed on 1.6 billion people across 70 countries twice a year and it’s called Day Light Savings. In the Spring when we lose one hour of sleep there is a subsequent 24% increase in heart attacks the next day. In the Autumn/Fall when we gain an hour of sleep, there is a subsequent 21% reduction. That’s how fragile our bodies are to even the smallest manipulation of sleep.

How much sleep is the right amount?

I’ll start with the latter, right now the recommendation is somewhere between 7-9 hours of sleep. Most human beings when you drop below 7 hours sleep, that’s when we can start to measure impairments in your brain function as well your body. So that’s the target 7-9 hours. In terms of ritual or tips.

what is the best way to get good night sleep and what are the health benefits?

I'll give you 5 tips.

1. Regularity.

Go bed at the same time and wake up at the same time, no matter if it is the weekend or a weekday. Regularity is key.

2. Keep it cool.

Your body needs to drop by about 1 degree Celsius in terms of its core temperature to initiate good sleep. That’s while you’ll always find it easier to fall asleep in a room that’s too cold rather than too hot. So a bedroom temperature of around about 18 degrees Celsius is good for most people.

3. Darkness.

We are a dark deprived society and we need darkness to allow the rise of a hormone called melatonin, so try to stay away from screens in the last hour before bed, also dim down half the lights in your apartment or your home in the last hour before bed. You’d be surprised at how sleepy it makes you.

4. Don’t stay in bed awake for very long.

If you’ve been in bed awake for maybe 20-25 minutes, get up and go to a different room, otherwise your brain learns the association that being in bed is about being awake. You need to break that association, only return to bed when you are sleepy and that way you will re-learn the association about your bed being the place of sleepiness.

5. Caffeine and Alcohol.

Try to stop drinking caffeine around midday if you are going to bed at 10pm. Alcohol is probably the most misunderstood sleep aide. Alcohol is a sedative and sedation is not sleep. If you drink in the evenings thinking that it helps you fall asleep it's important to know that you are just sedating your brain, which is not allowing it to go into natural sleep. Alcohol will also wake you up throughout the night, as it blocks your rem sleep, so you won't feel as rested the next day.

Victoria and I, are mothers and so are some of our community. What about all those sleepless nights? Can we catch up? Whats the best way to deal?

It’s difficult; can we catch up on our sleep? Not really, so sleep isn’t really like the bank, you can’t accumulate a debt and pay it off at a later point in time. So if I deprive you of sleep for an entire night and you lose 8 hours and then I give you all of the recovery sleep that you want on a second and a third night, you sleep more, but you never get back that full 8 hours. So there is no credit system in the brain where you can store up credit and then spend it on debt. So the best recommendation is if you have had a bad night of sleep accept it is going to be a bad day the following day. Just get to bed at the regular time the next day, have a good solid night of sleep and you will re-set. As for parents of young children I recommend working in shifts. One parent taking the morning shift and the other the evening shift so you still have solid regular sleep.

Habits we should be teaching our children about sleep? Where to start?

Gosh! It’s so important. There is a complete lack of sleep education in all developed nations and I have looked at this, none of them have a good curriculum. We teach them about physical activity, about diet, about risky behaviours yet we don’t teach them about sleep. So I truly don’t know where to start. What I am trying to do is work with the world health organisation to create a universal sleep education curriculum for children. Right now the best advice is for parents to celebrate sleep with their children and learn about sleep and then describe to them all the benefits of sleep.

Is there an ideal sleep position, pillow or mattress?

There is actually no particularly good data on any of this. There is no suggestion that one particular sleep position is better than the other, nothing about pillows or mattresses. I would say that if you are feeling like you are waking up during the night in pain because of physical discomfort due to your neck being propped up in a bad way because of your pillow, or your back because of your mattress, then you should think about replacing those things. But everyone is different. It’s like asking which size T-Shirt is best, well everyone is a different shape or size and it’s different for everyone. I would say though that the only thing about sleeping on your back is that if you are someone who snores (snoring is actually a sleep dis-order called sleep-apnia which is very dangerous and should be treated) lying on your back actually increases the probability of you snoring. That’s the only suggestion that I would offer where there is good clinical data to suggest that sleeping on your back is a bad idea.