The sense of dread arrives at dawn.
You're lying on your back, sheets rumpled, pillow clammy, when the birds begin to twitter.
Between a chink in the curtains you can see the sky turning from dark blue to pink as the sun prepares to rise.
The stars fade, and with them your hopes of a good night's sleep.
Even if you fall asleep immediately, you will only get a few hours of rest before your alarm begins to shriek.
You flip your pillow to the cool side in the hope that will help, but you know it's too late.
The sandman's absence has condemned you to a day of drowsiness and low productivity.
During the day ahead, your reaction times will be slow, your concentration shot.
If you're desk-bound, the words on your computer will blur and bleed into each other.
Shift workers, parents and anyone who has ever stayed up all night will be familiar with these symptoms: sluggishness, itchy eyes, a foggy head and general irritability.
But the effects of a lack of sleep are far worse than mere drowsiness.
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Alzheimer's disease, obesity, heart disease and cancer have all been linked to a decline in the quality and quantity of sleep.
Since the 1960s, we've decreased our average sleep time by about 20 per cent, according to Sleep for Health Managing Director and sleep specialist, Dr Carmel Harrington.
The World Health Organisation classifies shift-work as a probable carcinogen.
Leading sleep researcher Matthew Walker believes we're in the middle of an epidemic of sleeplessness.
He says less than two-thirds of adults get the required amount of sleep each night.
A neuroscientist and bestselling author, Professor Walker says sleep should be prescribed.
Sleep "restocks the armoury of our immune system", he says in his book, Why We Sleep: The New Science of Sleep and Dreams.
"Routinely sleeping less than six or seven hours a night demolishes your immune system, more than doubling your risk of cancer."
Disrupted sleep also exacerbates depression, anxiety and suicidal ideation, and driving while fatigued is one very direct way insufficient sleep can end lives.
In Australia, about 20 per cent of fatal road accidents involve driver fatigue, according to the Transport Accident Commission.
With 1253 lives lost on Australian roads in the 12 months to April 2018, that's 250 deaths that could potentially be put down to a lack of sleep.
Yet our culture promotes sleep deprivation.
Technology and globalisation have been major disruptors of our sleep but that's only part of the story.
People often link the ability to function on minimal sleep with success.
US President Donald Trump boasts about his ability to survive on as little as three hours of sleep a night, as if slumber is the domain of the lazy and weak.
Kevin Rudd was also famous for sleeping for as little as three hours a night.
Martha Stewart, fashion designer Tom Ford, Margaret Thatcher and Nikola Tesla are among those who qualify as the "sleepless elite".
Thomas Edison, whose literal light bulb moment is the reason humanity is now able to burn the midnight oil, condemned sleep as "heritage from our cave days", and slept as little as possible.
It's no coincidence that the World Health Organisation has declared that the loss of sleep in industrialised nations has reached epidemic levels.
Dr Harrington says technology has given us the ability to stay up all night but it is society that has given us the will to.
"Not only has there been an uprising in the 24-hour world, there's also been a cultural shift," she says.
"We tend to view our value by how busy we are … If we wear our busyness as our badge of honour, we're not going to give sleep value because that seems like we're lazy, or we're not worth a lot."
It is only since the electrification of the night in 1879 that we have had to think consciously about sleep.
"As soon as we shifted out of natural light cycles and got electric lights, we artificially stimulated parts of the brain," says Dr Fiona Kerr, Neural and Systems Complexity Specialist at the University of Adelaide.
"We changed the way melatonin [the hormone that controls our sleep-wake cycles] is produced and when it's produced."
Dr Harrington explains: "When we detect darkness, the message gets sent back from the eye to the middle of the brain and we start to produce melatonin. About an hour after we produce that, we will start to feel sleepy."
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Electric lights were the first disruptors but later gadgets have proved to be far more destructive to a good night's sleep.
These days, many of us sleep with our phones and iPads by our beds, ready to receive messages into the night – or we turn to our devices to try to overcome insomnia by playing games or watching TV.
We have failed to safeguard our sleep.
"Up until 10 years ago sleep was what we did, we didn't even think about sleep," Dr Harrington says.
"We're at a critical stage now because it's getting to a point where it is a problem."
Much like light bulbs, the bright screens of smart phones, laptops and iPads suppress then production of melatonin, so when you go to bed at 11 o'clock after staring at a screen, you won't be able to sleep.
There's also the aural interruption of the text message ping.
Our global lives mean an important email or social media alerts may arrive at 11.30pm.
You could disconnect completely, of course, but our phones are designed to prevent that.
"The more technology there is and the more immersive that technology is, the more disruptive it is," Dr Kerr says.
Our smartphones are designed to be extremely addictive.
When we hear the "ping" of a message, our brains release a little hit of dopamine, known as the "happy hormone".
"Part of your brain is always listening and ready and alert for the message," she says.
"So, there is a level of relaxation and deep relaxation that we don't get into."
If sleep was a product, companies would want to buy it, Dr Kerr says.
Not only does a decent amount of sleep lift your mood, enhance your logical reasoning, motor dexterity and working memory, it reduces stress, cuts the risk of heart attack and enhances your sex life.
It can also improve your creativity and help you "grow" your brain.
"In your brain you get things called glial cells that clean off plaque," Dr Kerr says.
The longer we sleep, the greater the benefits.
In the last hours of sleep, we enter what Dr Kerr calls abstraction mode. The first cycles of sleep are about "cleaning". In about the sixth hour of sleep, you begin consolidating new information gained during the day.
"Your brain basically says, I've done some maintenance, I'm now going to file this into long-term memory where we can keep it and be able to build on it," Dr Kerr says.
"In the late cycles of sleep you have a change in the chemicals that come into your brain. It creates not only learning but it allows you to build new brain and be creative and cross-connect things that don't normally get connected."
When your frontal lobe shuts down in sleep, creative thought is unleashed.
This is why you often wake having solved a problem, or having had a brilliant creative breakthrough.
After trying to understand why we sleep, Professor Walker came to the conclusion that there was not a single human function that didn't benefit from sleep.
It is as important as eating and exercise.
Authorities are now recognising sleep as the third pillar of health.
"If we deprive rats of food, water and sleep, they will die more quickly from lack of sleep than lack of food. The thing that will kill them most quickly is lack of water, the next thing is lack of sleep and the third thing is lack of food, which takes a few days longer," Dr Harrington says.
One University of Chicago study injected cancer cells into two batches of mice.
One batch, which was allowed to sleep comfortably and deeply through the night, developed small, confined tumours.
The other batch, which lived in a cage designed to repeatedly disrupt their sleep, developed large, aggressive tumours that spread through their muscle and bone.
The study leader, Dr David Gozal, has stressed that we need to make sure sleep is part of our culture.
We have recognised the need to address the other two pillars of health.
We've embraced yoga, Pilates, cycling, cross-fit and zumba.
We relish slow-cooked food and spend our weekends at farmers' markets, seeking fresh produce.
But we're still lagging behind when it comes to sleep.
"You get to the point where you don't cope when you're not sleeping well," Dr Harrington says.
This is something she has witnessed in her practice and her life.
"People do silly things. They feel they can't cope. They give everything up and six months later regret it ... When we don't get the chance to reset our brain and body, it can be a disaster."
Fortunately, Professor Walker says, the solution to this problem is one of the easiest and most enjoyable prescriptions to fill.
We just need to learn to prioritise sleep.
● Avoid sleeping during the day
● Don't drink caffeinated beverages after midday
● Avoid alcohol
● Daily exercise is good for sleep, but not within three hours of bedtime
● Try to finish eating roughly two hours before you go to bed
● Maintain a regular bedtime and waking time, and adopt a regular bedtime routine that includes at least one hour of winding down time
● Put away laptops, iPads and smartphones at least an hour before bed, dim household lighting and dismiss the worries of the day
● Make your bedroom a relaxation retreat. Use it only for sleeping, relaxation and romance
● Keep the bedroom cool, dark and quiet
● Invest in a comfortable mattress and pillows and keep your bed linen soft, clean and cosy
● A few slow, deep breaths, a relaxation exercise, a gentle yoga stretch, a relaxing visualisation or prayer can be valuable elements in your winding down routine
● Some people swear by a drop of lavender oil on the temples and pillow, others a warm bath or shower
● If sleep is still elusive, try keeping a sleep diary to help identify the patterns in your life that might be leading to sleepless nights
● If you still have trouble sleeping, see your GP to check if you have sleep apnoea or if there is some other physical or psychological reason why your sleep is disturbed
● Some natural remedies and supplements, including melatonin and magnesium, have been recommended as remedies for insomnia, but consult your doctor
If you, or someone you know, needs to talk to someone, call Lifeline on 13 11 44. Or, if it is an emergency and you're experiencing a crisis, call 000 NOW.