The benefits of a good night's kip cannot be underestimated. Getting your eight hours in improves your memory, makes you more alert and productive, reduces stress, helps you lose weight and staves off the risk of colds, flu, heart disease, diabetes and depression. In fact, good quality sleep over a long-term period may even increase life expectancy by up to seven years.
But while shut-eye is crucial to wellbeing, many of us struggle to get enough of it. Whether we're burning the midnight oil, out painting the town red or up to the early hours worrying, the quality and quantity of our sleep is being constantly eroded.
Here are ten simple and sometimes unexpected ways that have been scientifically proven to improve how well you sleep, from eating kiwis to sitting by a window at work, keeping your feet outside the covers and listening to classical music.
Read on and let the deep sleep roll...
1. Drink tart cherry juice twice a day
Drinking tart cherry juice twice a day can help you sleep nearly 90 more minutes a night, according to new research presented at the Experimental Biology 2014 conference earlier this year.
Researchers at Louisiana State University used a test group of seven insomnia-suffering adults. They drank eight ounces of Montmorency tart cherry juice twice a day for two weeks, followed by two weeks of no juice, and then two more weeks of drinking a placebo beverage.
The group were observed to see how quickly they fell asleep and how long they stayed sleeping.
When they drank a sour cherry juice in the morning and at night, participants were able to sleep an average of 84 minutes more each night, compared to the weeks in which they drank the placebo drink.
In addition, their sleep was less disrupted during that time.
Study co-author Frank L. Greenway said cherry juice contains relatively high levels of melatonin, the chemical which helps moderate the body's sleep-wake cycle to produce feelings of sleepiness at night and wakefulness during the day.
He noted that drinking cherry juice or eating dried cherries could be a healthier natural alternative to using sleeping pills in overcoming sleep problems.
Another survey by University of Texas researchers in 2010 also concluded that cherry juice blend could have modest but beneficial effects on sleep in older adults with insomnia.
"When consumed regularly, tart cherries may help regulate the body's natural sleep cycle and increase sleep efficiency, including decreasing the time it takes to fall asleep," said scientist Russel J. Reiter, Ph.D, one of the world's leading authorities on melatonin. "And, because cherries are so rich in other antioxidants, such as anthocyanins, you get other important health benefits."
2. Block 'blue light' at night and use a sleeping mask
For some years now, researchers have been building on a link between sleep problems and the use of artificial lighting and electronics - or so-called "blue lights" - at night. Modern light bulbs and electronic devices such as computer screens emit large amounts of blue light. That's fine when it is actually daytime - but during the late evening, this light tricks our brains into thinking that it is daytime.
This disrupts the brain’s natural sleep-wake cycles and inhibits the hormone melatonin, which signals to our bodies and brains when it is time to go to sleep.
A 2011 paper on the effects of blue light found that chonnically exposing oneself to electrical lighting in the late evening disrupts melatonin signaling and therefore quality and quantity of sleep.
So it's a good idea to cut down on blue light levels a few hours before you go to sleep. You could do this by getting a red or orange reading lamp (which doesn’t emit blue light) keeping your bedroom completely dark with light-blocking blinds or using a sleeping mask. You could even install a programme called F.lux on your computer, which adjusts the colour and brightness of your screen based on your timezone.
It's also a good idea to get plenty of natural daylight during the day, in order to properly regulate your body's melatonin levels and sleep-wake system.
3. Exercise moderately at least 150 minutes a week
We all know exercise is important to general well-being, so it comes as no surprise to learn that regular activity improves sleep quality.
A 2010 study from Northwestern University in Illinois tested a group of 23 sedentary adults, around half of whom reported impaired daytime functioning through lack of sleep.
They found that participants who exercised regularly reported that their sleep quality improved, raising their diagnosis from poor to good sleeper over a 16-week period of physical activity (which consisted of a 30-40 minute workout exercising to 75% of their maximum heart rate four times a week).
This compared to a control group of participants who didn’t exert themselves physically but only mentally - and reported no improvement in sleep quality.
"Better sleep gave them pep, that magical ingredient that makes you want to get up and get out into the world to do things," said lead author Kathryn Reid, PhD, of the Department of Neurobiology and Physiology at Northwestern University. "Now we have promising results showing aerobic exercise is a simple strategy to help people sleep better and feel more vigorous."
The findings were backed up with a larger sample study published by Oregon University in the journal Mental Health and Physical Activity in 2011. It found that, out of a group of 2,600 men and women, ages 18-85, people sleep significantly better and feel more alert during the day if they got at least 150 minutes of exercise a week. In fact, that 150 minutes of moderate to vigorous activity led to a 65 percent improvement in sleep quality among the study's volunteers.
Another 2011 study among a group of individuals suffering from primary insomnia found that long-term aerobic exercise on a moderate level elicited the best improvements in sleep, quality of life and mood.
The kind of sleep you have may even be affected by when in the day you work out. A survey on sleep deprivation in Japan (a country where lack of sleep is a major health issue) found that sleep duration was greater among participants who exercised in the afternoon, compared to those who exercised in the morning.
4. Sit next to a window at work
A study published in the Journal of Clinical Sleep Medicine this month found that employees exposed to natural light slept 46 minutes longer—and more soundly in general—than their peers working in windowless offices did.
Researchers at the University of Illinois compared the self-reported sleep patterns of 49 employees, 27 of whom worked in windowed offices and 22 in windowless environments.
They then equipped 21 participants (10 windowless workers and 11 windowed ones) with a wristband that measured activity during sleep and waking hours.
Data from the bands revealed that workers with windows slept 46 minutes longer each night during the work week, had fewer sleep disturbances than their windowless counterparts and were four times as active during the workday.
The results showed that even on non-work days, employees with windows got more rest and slept better and for longer.
"Light exposure in the workplace may therefore have long-lasting and compounding effects on the physical and mental health of the workers, not only during but also beyond work hours," the paper concluded.
Deprivation of natural light can confuse the production of melatonin, the hormone that controls your body clock and sleep-wake cycle by chemically triggering feelings of drowsiness.
Mohamed Boubekri, leading the study, recommended that "architectural design of office environments should place more emphasis on sufficient daylight exposure of the workers in order to promote office workers’ health and well-being".
5. Buy a good quality mattress at least every 10 years
Yes, a good mattress really can impact the quality of sleep you have. A 2008 study by Oklahoma State University study showed that a new quality mattress provided sleepers with 71 percent improvement in sleep comfort and 62 percent improvement in sleep quality.
It also linked sleeping on a new mattress to reduced back pain, stiffness and shoulder pain. And according to the study, those initial benefits applied regardless of participant age, weight, height or body mass index.
"Our work showed that new mattresses have a considerable impact on reduced back pain and improved sleep quality, among other benefits," said lead researcher Bert Jacobson. "Based on our research, there’s no question that a new mattress can sustain these benefits for just about anyone, regardless of age, weight or gender.
"Timely replacement and mattress quality can have a very positive impact on sleep and overall quality of life."
What constitutes a good mattress depends on your individual needs (whether you have back pain, allergies etc.); there's no one definition beyond replacing it at the right time.
"It's really important for people to realize that mattresses have a certain lifespan," says Michael Decker, PhD, associate professor at Georgia State University and spokesman for the American Academy of Sleep Medicine.
He recommends keeping your mattress for no more than 10 years and adds that when shopping around for the right replacement, "people should not be embarrassed to go into a store and lay on a mattress for 20 minutes."
6. Cut down on how much alcohol you drink
A strong nightcap might do the job in sending you off to sleep but scientists have found that alcohol-induced snoozing is of poorer quality than normal sleep as it reduces rapid eye movement (REM) - the crucial restorative stages of shut-eye.
A 2013 study by The London Sleep Centre found that the immediate and short-term impact of alcohol was to reduce the time it takes to fall asleep - however, that was offset by having more disrupted sleep in the second half of the night.
And the more a person drinks, the greater the disruption to sleep.
"Alcohol may seem to be helping you to sleep, as it helps induce sleep, but overall it is more disruptive to sleep, particularly in the second half of the night," said researcher Irshaad Ebrahim.
"Alcohol should not be used as a sleep aid, and regular use of alcohol as a sleep aid may result in alcohol dependence."
"Deep sleep is when the body restores itself, and alcohol can interfere with this," says Dr John Shneerson, head of the sleep centre at Papworth Hospital in Cambridge. "As the alcohol starts to wear off, your body can come out of deep sleep and back into REM sleep, which is much easier to wake from. That's why you often wake up after just a few hours sleep when you've been drinking."
According to drinkaware.co.uk, in the course of a night you usually have six to seven cycles of REM sleep, which leaves you feeling refreshed. However, if you've been drinking you'll typically have only one to two, meaning you can wake feeling exhausted.
Other drugs may also affect sleep quality. A survey earlier this year from the University of Pennsylvania found that people who used cannabis in their early teens were twice as likely to have severe sleeping problems in later life.
"The most surprising finding was that there was a strong relationship with age of first use, no matter how often people were currently using marijuana," said lead author Jilesh Chheda.
"People who started using early were more likely to have sleep problems as an adult."
7. Sleep in a cool setting, with a room temperature of around 18.5ºC
Sleep experts differ on the exact temperature needed for a good night's snooze but most are agreed that cooler is better - within the region of 16 and 19 degrees Celcius (60 to 67 degrees Fahrenheit). A hot sleeping environment (above 24ºC) leads to more wake time and lighter sleep at night and if it's too cold (below 12ºC) you may also struggle to drop off or stay asleep.
But cooler is better in general because as you go to sleep your body temperature drops anyway, so a cool room will help speed up this process.
"When you go to sleep, your set point for body temperature - the temperature your brain is trying to achieve - goes down," H. Craig Heller, PhD, professor of biology at Stanford University, told Wedmd.com.
"Think of it as the internal thermostat. If you are in a cooler room, it is easier for that [the drop in body temperature] to happen."
He noted that a cooler room temperature is also important when it comes to the quality of REM (rapid eye movement) sleep, the stage which is generally thought to be most restorative and leave you feeling most refreshed.
Added to this is findings from a 2006 study which concluded that insomniacs have impaired heat loss when attempting sleep, with a core body temperature that was significantly higher than good sleepers; again indicating that lower body temperature is important to quality shut-eye.
All in all, a slightly cool room and a lower core temperature are optimal for sleep. The American Academy of Sleep Medicine recommends thinking of your bedroom like a cave: cool, quiet and dark. Be aware of the bedding you use - comforting items such as thick blankets or pillows may inadvertently make you too hot during the night.
8. Sleep with your feet outside the covers
As an extension of keeping cool during the night, it may help to keep one or both feet outside of the bed covers as you sleep. US-based National Sleep Foundation spokesperson Natalie Dautovitch recently shared the tip with the journal Science of Us.
The connection here is cooling down; as outlined above, your body temperature starts to drop when you fall asleep and in the deepest stages of sleep, your body is at its coolest (about one or two degrees below normal).
This is why routines such as taking a warm bath or drinking a warm beverage before you go to bed help with sending you off to sleep, Dautovitch says.
It's not the warmth here that aids sleep but rather the cooling down process that occurs after you step out of a bath or finish a warm drink. Keeping your feet out from under the duvet works in a similar cooling-down fashion.
"I think it’s likely in service of trying to cool our bodies down because we’ve gotten too warm to sleep," Dautovitch explains.
Feet, in particular, are good for this purpose because they contain blood vessels called the arteriovenous anastomoses, which along with the lack of hair on the bottom of your feet, mean they are ideally designed to help dissipate body heat.
Couple this with the knowledge scientists have about cooler temperatures aiding sleep and it's very credible that "sticking your toe out or your foot out could bring you to a more restorative sleep," Dautovitch says.
9. Eat two kiwis a day, an hour before bedtime
Kiwi may be the unexpected super-fruit behind a good night's sleep. Researchers at Taiwan’s Taipei Medical University found that eating kiwi on a daily basis was linked to substantial improvements to both sleep quality and sleep quantity.
Their 2011 study looked at 22 women and two men between the ages 20-55, all of whom were experiencing some form of sleep disruption.
The participants ate two kiwifruit a day one hour before bedtime for four weeks in a row. Their sleeping habits were then monitored via sleep diaries, a standard sleep-quality questionnaire, and wristwatches that measured aspects of sleep quality and quantity.
Researchers concluded that sleep quality improved in a number of ways within the four-week period. The time it took for volunteers to fall asleep decreased by 35.4%, with the amount of wakefulness during the night also falling by an average of 28.9%. The total sleep time among the volunteers increased by 13.4%, with sleep efficiency (total amount of time spent sleeping compared to total amount of time spent in bed) increasing by 5.41%.
So what's the secret of a humble kiwi? The high level of antioxidants found in this fruit may go some way to explaining its sleep-promoting qualities - previous studies have shown that poor sleep is associated with decreased antioxidant levels.
Kiwis also contain lots of serotonin, the "happy hormone" that's crucial to initiating the onset of sleep and maintaining the sleep cycle during the night. It's serotonin that regulates transition through stages of sleep, including the deepest, slow brain wave delta sleep stage.
As an added bonus, kiwis contain loads of vitamin C to reduce blood pressure and high levels of potassium to aid respiratory function. So it's good news all round, basically.
10. Listen to "soft" classical music before bedtime
A 2005 study by the Buddhist Tzu-Chi General Hospital in Taiwan showed that listening to soft music at bedtime helped older adults sleep better and longer.
The groundbreaking research, published in the The Journal of Advanced Nursing, found that older people (aged 60-83) with sleep problems reported a 35 percent improvement after they started listening to 45 minutes of soft music before bedtime.
"The difference between the music group and the control group was clinically significant," said Hui-Ling Lai, lead author of the study. "The music group reported a 26 percent overall improvement in the first week and this figure continued to rise as they mastered the technique of relaxing to the sedative music."
And it may not only be the elderly who benefit from the sleep-inducing effect of music. A 2008 study found relaxing classical music to be an effective intervention in reducing sleeping problems among a test group of 94 students aged between 19 and 28 years.
Participants listened for 45 minutes either to relaxing classical music or an audio book at bedtime for three weeks. The audio book group also reported an improvement in sleep quality, but it was not so marked as the classical music group.
Finally, 2008 research by the University of Tübingen in Germany found that listening to music while you sleep can improve the quality of your sleep - but only if the music in question is synchronised to the rhythm of the slow brain oscillations you undergo when asleep.
If that sounds a little too technical for your average bedtime routine, the bottom line is: auditory stimulation at low intensities (e.g. easygoing classical music) can enhance sleep rhythms.
Listening to soft classical music will also introduce a sense of ritual into your bedtime routine - which is important in itself.
"Rituals help signal the body and mind that it's coming to be time for sleep," explains Dr. Karen Carlson, associate professor of medicine at Harvard Medical School.
Photos: Rex Features