Struggling to get to sleep or sleep through the night?
You're not alone - the says that around one-third of adults experience sleep problems at least once a week, with up to one in ten permanently plagued by chronic insomnia (which is defined as difficulty getting to or staying asleep most nights for longer than four weeks).
We ask Professor Guy Leschziner, professor of neurology and sleep medicine at Guy's Hospital Sleep Disorders Centre, and author of The Secret World of Sleep, about the science behind getting a better kip.
Get the lowdown on free ways to improve your sleep habits, and if any sleep aids really work.
Many factors can hamper your ability to get a good night's sleep, and both biological and psychological influences are at play.
Professor Leschziner says: 'Daytime stress causes causes physical and psychological 'activation' or disruption which will make sleep more difficult or of a poorer quality.'
Over time, positive conditioned responses (such as 'bed is a restful place') may get displaced by negative ones (such as 'bed is somewhere I now associate with not being able to sleep'), creating a vicious cycle.
In most instances, disturbed sleep can be helped by addressing 'sleep hygiene' and establishing good practices, such as:
Professor Leschinzer says: 'It might sound counter-intuitive but depriving yourself of sleep can enable your brain to re-establish a proper sleep schedule.'
Note down how much time you actually spend asleep on a typical night - as opposed to tossing and turning - then allow yourself to sleep for this amount of time plus 30 minutes.
For example, if you are trying to sleep for eight hours but only managing five, spend five hours and 30 minutes in bed - based on the time you want to get up and altering your bedtime accordingly - and gradually increasing it once you're spending the majority of time in bed sleeping.
If you have a smartwatch or fitness tracker the sleep tracking function may help you understand aspects of your sleep, but Professor Leschziner suggests using them with caution as the information could be inaccurate and could even fuel your anxiety - causing further sleep issues.
Our body temperature drops by a couple of degrees when we are sleeping to help conserve energy for vital functions such as breathing.
If it's too cold (under about 12°C) it can be difficult to drop off, and if it's too hot (24°C or more) this can lead to a restless sleep.
We typically sleep better when the room is cooler - ideally around 16-18°C.
A fan, air conditioner or heater can help you to help achieve a suitable bedroom temperature, but opening a window, or if its cold piling on the blankets, can also help. Bed socks can also make a big difference if you're feeling chilly.
The type matters too. When we surveyed Which? members about mattresses, those who have an open coil mattress were less likely to say it helps them get a good night's sleep than those with other types of mattress.
Lie for around five to ten minutes on several mattresses when you're trying them out, remembering to try turning on them to see how comfortable this is, too.
If you sleep with a partner, bear in mind any differences in weight and size between you both, as this affects what type of mattress will suit you best.
If you're not sleeping properly, exposing yourself to natural light in the morning can help reset your 'body clock' so you'll sleep more easily at bedtime.
Daylight in direct sunlight has up to 10,000 lux (bright office lighting is generally less than 500 lux) which is why daylight is so powerful at helping to reset the sleep-wake cycle.
Conversely, blue light emitted by many devices including smartphones and laptops has been found in multiple studies to contribute to poor sleep and excessive daytime sleepiness.
Stop using screens an hour before bedtime - even if they are in night mode, to avoid overstimulation preventing good sleep.
A published in the journal Sleep Medicine Reviews found that taking a warm bath or shower of 40-42.5 °C one to two hours before bedtime improved sleep quality and sleep efficiency (the time spent asleep when you're in bed), and reduced by an average of 10 minutes the amount of time it takes to drop off to sleep.
During the night our temperature drops and this aids better sleep, so although it sounds counter-intuitive, warming ourselves up by immersing ourselves in warm or hot water a little while before we go to bed actually helps to aid this natural drop.
The way it does this is by taking heat away from the body's core and to the hands and feet from where it is dispersed.
If sleep hygiene doesn't seem to be helping, online self-help apps offering cognitive behavioural therapy for insomnia (CBT-I) can be an effective insomnia solution - and in some cases even better than face-to-face therapy.
found that - a six-week digital treatment for insomnia - helped those with insomnia gain almost six hours more sleep a week, as well as reducing sleeping pill use, time off sick and the number of GP visits.
CBT-I helps you to identify thoughts and behaviours that are causing your sleep problems and replace them with more constructive ones to promote healthy sleep through better habits.
There is some research about the effectiveness of lavender essential oil in improving sleep quality, however, there aren’t any specific studies about pillow sprays, room mists, aromatherapy diffusers or roller-ball aromatherapy applications benefitting sleep.
Professor Leschziner says the benefit may come from involving them in a sleep ritual that helps you to prepare for a good night's sleep.
Professor Leschziner says: 'There is some suggestion that magnesium may help with sleep in people who have restless leg syndrome, but it's anecdotal evidence only.'
The same study also suggests that because oral magnesium is very cheap and widely available, adults with insomnia might like to try it (in quantities of less than 1g three times per day) to see if it helps.
This hormone plays a key role in regulating sleep and can be taken as a supplement, but it can't be bought over the counter in the UK. Some people may qualify for it on the NHS, though typically for short-term use - see ).
Professor Leschziner says: 'It's been demonstrated that melatonin can be helpful in terms of the time it takes to get to sleep and the quality of that sleep but the long term effects aren't fully understood.'
Cannabinoids like CBD have become trendy in the past few years and some people swear they can help you sleep.
However, Professor Leschziner says: 'The jury is still out on the long term consequences of it as an aid for sleep. There is more research to be done.'
A says that existing research into its use for insomnia is insufficient and further high-quality trials are needed before any conclusions can be drawn about their use for aiding a better night's sleep.
So, trying simple routine and sleep hygiene changes is likely to be the best place to start (and cheaper!).