1. YOU'RE CHECKING FACEBOOK IN BED
Using a smartphone or tablet can keep you up longer than intended, as it emits a high concentration of blue light which delays the release of sleep-onset hormone melatonin.
A 2014 Harvard study which compared reading on devices and printed books found that those who used tablets took longer to fall asleep and had higher alertness before bedtime.
2. THAT MID-AFTERNOON ESPRESSO...
It's well-known that drinking coffee before bed can keep you up for longer, but in 2013 American scientists discovered that even an afternoon cup can make falling asleep a challenge.
The study found that consuming caffeine even six hours before hitting the hay has a detrimental effect on falling asleep and reduced the total nightly sleep amount by more than one hour.
3. YOU HAD A BIG MEAL
Eating a main meal late in the evening increases blood flow to the digestive tract, prompts the stomach to produce gastric acid, and forces muscles to get to work to metabolise food when the entire system should be slowing down in order for the body to fall asleep.
4. IT'S A FULL MOON
Researchers at the University of Basel in Switzerland found that the lunar cycle affects human sleeping patterns, although it is not clear why.
During a full moon, subjects of a 2013 study took five minutes longer than normal to fall asleep and had 20 minutes less sleep throughout the night.
5. BLAME YOUR OTHER HALF
A 2009 study carried out at the University of Surrey found that couples sharing a bed suffer 50 per cent more sleep disturbances than people who slept alone.
6. ARE YOU A SMOKER?
Smokers suffer 'significantly longer sleep onset latency' - meaning it takes longer for them to fall asleep - a 2013 study found, explained by the stimulating effect of nicotine as well as withdrawal symptoms at bedtime.
7. IT COULD BE DEPRESSION
A common reason for not being able to fall asleep is that your mind is racing with thoughts. However, if this occurs on a regular basis it may be a mental illness that needs treatment.
Chronic anxiety is an illness on its own, but also often a symptom of another, such as depression. Cognitive behavioural therapy (CBT) is recommended by the NHS as a treatment, with high success rate for anxiety and insomnia.
8. IT'S YOUR NIGHT-TIME TREAT
Switching from milk to dark chocolate has many health benefits, however it's not so good for you if you nibble it before going to bed. Dark chocolates contain higher levels of caffeine than milk varieties.
While an average cup of coffee contains 100mg of caffeine, a 100g bar of plain chocolate can be expected to contain just under 50mg of caffeine (with milk chocolate on average less than 20mg per 100g), according to the NHS.
9. IT'S THE MENOPAUSE
Mid-to-late life is a time of stress for many women, as the menopause brings on both mental and physical changes which can trigger anxiety. In addition, hot flushes can cause difficulty for some women when they want to get to sleep. Treatments such as HRT, which can be prescribed by your GP, may help resolve these problems.
10. YOU HAVE NOCTURNAL ASTHMA
Asthma is increasingly common, with its prevalence increasing by 50 per cent each decade. However for some sufferers, symptoms only occur when lying down - often at night - and this is a condition known as nocturnal asthma.
It is caused by a combination of factors, such as lung function declining in late evening and a sleeping position that leads to the restriction of the airways and sinus drainage into them.