You probably get tetchy when you’ve had a bad night’s sleep, right? But too little of that zzz-elicious time between the sheets can do more than just make you a bit grumpy, it can have a serious impact on your mental health. So with the average person in the UK sleeping 90 minutes less per night than we did 100 years ago, it’s time to wake up and smell the coffee (just don’t drink too much of it after lunchtime).
The link between sleep hygiene and mental health is already well established. The two most common sleep disorders are: insomnia (an inability to fall or stay asleep) and obstructive sleep apnoea or OSA (a condition whereby your breathing stops and starts during sleep, waking you up regularly throughout the night). Large-scale studies have shown that insomniacs are 10 times more likely to have clinical depression and 17 times more likely to have clinical anxiety than the general population.1 People with OSA don’t fare much better- they are 5 times more likely to have clinical depression.
And it’s not just major sleep conditions that affect our mental health – even slight reductions in sleep can affect us in ways we might not have imagined. Having only 4-5 hours sleep a night for one week has been shown to reduce judgement, memory and mood leading to fatigue, tension, confusion and anxiety.
Which came first? Just because they are linked doesn’t necessarily mean that lack of poor sleep causes poor mental health. It could simply be that those suffering from mental health conditions find it hard getting to sleep?
In reality, it appears to be a much more complex picture with both influencing each other, often becoming a vicious cycle – for example, insomnia leading to anxiety leading to further insomnia leading to further anxiety.
Although scientists argue about the causality – which comes first – there is plenty to suggest that poor sleep is one of the factors that cause poor mental health. For instance, it seems that the path from insomnia to depression can be predicted from an early age. One team interviewed 4400 teenagers without any history of depression, and then returned to the same group 6 years later. The results showed that those who suffered from insomnia at the start were up to 3.5 times more likely to develop depression later on and were also significantly more likely to abuse drugs and alcohol.
Furthermore, treating sleep disorders can also improve the associated mental health disorders. In a study of patients treated for OSA, they showed a lasting and significant reduction in their symptoms of depression.
Many people now wear FitBits and other devices to measure their sleep, but what happens during those strange cycles of brainwave activity? It turns out that both NREM (deep sleep) and REM (dream sleep) play a part in keeping you happy and sane.
In deep sleep, your muscles relax, heart rate slows and your immune system has a chance to repair itself from the carnage you’ve brought about by your day spent breathing in other people’s germs, eating deep-fried carbohydrates and the constant reminder of impending doom from the news.
During dream sleep, our body becomes alert again and our brain sets about reviewing all the new information it’s taken on board and deciding what to keep, such as the embarrassing memory of the clumsy flirtation you attempted on your new colleague, and what to forget, such as your nan’s birthday or which pocket you left your keys in.
Both types of sleep are needed to promote clear thinking, and robust mental and emotional health by regulating the stress hormone cortisol, balancing our neurotransmitters, and reducing hyperactivity in the amygdala, our brain’s emotional centre. A lack of sleep can, therefore, lead to brain fogginess, poor judgement and decision-making, negative thinking and emotional vulnerability.
And why stop at mental health when a good night’s kip offers such a sleeptacular array of other proven benefits?
Even if you’re sceptical as to how much your mental health condition can be cured by simply sleeping better, perhaps having more energy, looking more attractive, being able to control your weight, having a better sex life, not getting ill as often, having better skin, eyes and hair, an improved memory and creativity, or performing better in work or sports might be persuasion enough to take staying in bed more seriously.
For those with diagnosed sleep disorders, there are various tools that can help. Cognitive behavioural therapy for insomnia (CBT-I) and continuous positive airway pressure (CPAP) for OSA have been known to help.
For the rest of us, there are many small changes we can make to improve our sleep.
Sounds pretty obvious but staying up late reading this article or watching a documentary about serial killers isn’t ideal. Even sleeping 60 minutes more can make you happier and healthier.