The theme for Mental Health Day on 10th October 2023 is “Mental health is a universal human right”. 

Mental health exists on a spectrum; while we all have good days and bad days, it is estimated that 1 in 6 adults experience a common mental health disorder such as depression or anxiety at any point in time. Mental health disorders make coping with everyday demands difficult and can disrupt someone’s ability to work, look after their family and enjoy a good quality of life.

In the UK, the NHS offers a range of evidence-based treatments and support for mental health disorders, including psychological therapies, but the nature of mental health disorders means that many people may not feel confident, able or motivated to ask for help.

There is therefore a lot of interest in how to help people improve their own mental health and prevent mental illness.

Fortunately, there is one activity which is completely free of charge, and requires no specialist knowledge, that we can all do i.e. is universally accessible: getting the right amount of good quality sleep.

How is sleep linked to mental health?

Disrupted sleep and fatigue are symptoms of all common mental health disorders including anxiety, depression, PTSD, psychosis, and schizophrenia. In depression, both too little and too much sleep (‘hypersomnia’) can be signs of the illness.

Poor sleep used to be seen as simply a symptom, or early warning sign; the canary in the mineshaft of poor mental health.

Twenty years ago if you went to see your doctor about a sleep problem, you’d often be prescribed a drug to treat depression or anxiety, which was assumed to be the underlying cause. In the last few decades, we’ve come to realise that sleep is not just an indicator, it’s also a driver of mental health. The relationship between sleep and mental health is bidirectional.

Insomnia sufferers are at more than twice the risk of developing future depression or anxiety. Even with successful treatment, poor sleep is a risk factor for relapse.

Why does poor sleep impact mental health?

To understand how lack of sleep affects emotional health, it is helpful to think back 200,000 years to when our ancestors were living as hunter-gatherers. In those days, sleep was likely to be disrupted by danger, such as predators, storms, hunger or threats to our survival.

When we compress our sleep, our brain responds as if we’re under threat. The emotional centres go on high alert; they get hyper-sensitive. In particular, the amygdala, which controls our fight or flight stress response, gets 60% more sensitive to negative threats after 24 hours without sleep.

So, things that would feel like an achievable challenge on a well-slept day feel disproportionately worrying when we’re short of sleep.

While the brain focuses its attention on survival, it funnels glucose away from our prefrontal cortex. This means we have less capacity in the areas of the brain responsible for forward planning, strategic thinking, and self-control. We become less able to concentrate, we revert to learned patterns of behaviour – such as reaching for our phones as a distraction – and we are more likely to indulge in high-risk activities.

From a health behaviour perspective, the sleep-deprived brain is more likely to neglect the things which could help make us happy: we feel less motivated to exercise, less willing to socialise with friends, and are more likely to crave fast food for quick energy bursts. We are more prone to using caffeine to stay alert, or to rely on alcohol in an attempt to switch off – all of which make sleep worse.

Our sleep-deprived minds also narrow their focus towards any perceived threats, such as work deadlines, or relationship problems. We become more likely to worry excessively.

Eventually, we may develop a fear of not being able to sleep. Beliefs about sleep can become unhelpfully distorted. We lie there, catastrophising about the terrible things that will happen if we don’t get to sleep, or if we never sleep again. Negative thoughts about not sleeping can make us more tense and less likely to sleep well, which then further increases the likelihood of more emotional disruption the following day, and a cycle of hyperarousal continues.

Can better sleep improve mental health?

The positive part of the bidirectional relationship is that sleep improvement can have powerful effects on mental health symptoms.

In the first study to investigate this idea that I was involved with, we took 100 NHS patients who were on the waiting list for treatment for mild to moderate anxiety or depression and were also sleeping badly.

We gave them access to an online sleep education programme, based on cognitive behavioural therapy for insomnia (CBT-I). After six weeks of focusing on their sleep, 68% of these patients had moved to recovery from anxiety or depression, versus a national average of 50% for psychological therapies. They were only getting help with sleep – they received no other treatment.

This was encouraging, but it was only a small study, so researchers from the University of Oxford set out to do something a bit more elaborate. In the largest-ever trial of psychological therapy, they recruited over 3,700 students from 26 universities with trouble sleeping and randomised them to either a sleep improvement programme or a waitlist control group.

After 10 weeks, not only had the sleep improvement group improved their sleep but they also had reductions in paranoia, hallucinations, depression, and anxiety – all of which were mediated by improvements in insomnia symptoms.

We now have data from 65 different trials in thousands of people which have consistently found that better sleep can unlock improvements in all aspects of mental health including stress, rumination and overall well-being.

There is a dose-response relationship: greater improvements in sleep quality lead to greater improvements in mental health. So wherever you are on the spectrum of poor sleep, the odds are that even small improvements could generate a small improvement in wellbeing.

So, better sleep can be a catalyst for better mental health. It can also give us more energy, more focus, and more self-control. All we have to do is find a way to tackle the negative cycles of lack of sleep, stress, unhelpful thoughts and unhelpful behaviours.

How can you improve sleep and mental health?

The first line of recommended therapy for chronic insomnia disorder is Cognitive Behavioural Therapy for Insomnia (CBT-I). This is an approach targeting the thoughts and behaviours which make insomnia persist. It can be delivered 1-2-1 or in groups, as a self-help programme online, or even in a book.

CBT-I is a toolkit approach; you apply the tools which are most relevant and helpful to you.

Here are the main ingredients of CBT-I:

• Sleep hygiene. Most of the advice you will have heard about good sleep habits is called “sleep hygiene”. This includes getting out of bed at the same time every day, regular exercise, dimming the lights, winding down before bed, and limiting caffeine and alcohol. While useful for improving sleep for many people, this type of advice alone is usually insufficient for people with chronic insomnia.
• Monitoring using a sleep diary. Keeping a sleep diary can help you to spot patterns, and track progress. You may realise that your sleep is not as bad as you thought. You can also track your sleep efficiency, the proportion of time in bed that you’re asleep. The target is > 85% sleep efficiency.
• Stimulus control. The goal is to develop a positive sleep-bed connection, so, you only use your bed for sleep, and intimacy, and nothing else. You only get into bed when you are sleepy, and get out of bed after 15 minutes if you can’t sleep, rather than lying in bed getting frustrated that you can’t sleep.
• Relaxation techniques. Relaxation techniques help to overcome the hyperarousal, or overactive stress response associated with chronic insomnia. This might include breathwork, positive imagery or progressive muscle relaxation. The advice is to practice every day, to make relaxation easier. Mindfulness meditation is also sometimes included in CBT-I.
• Sleep restriction. The goal of sleep restriction is to improve sleep efficiency by reducing time in bed, and helping people to sleep through the night. For example, if you are usually in bed for nine hours, but you only sleep for six, you would be advised to stay in bed for six hours. Although this is likely to make you tired in the short term, the additional sleep pressure has been found to help consolidate broken sleep. Even as a standalone treatment, when supported by a weekly call with a nurse, sleep restriction therapy over 4 weeks has been found to improve both insomnia and depressive symptoms.
• Cognitive reframing. In this exercise, you are encouraged to write down the negative thoughts that you have about sleep, and to consider more helpful alternatives. By identifying and challenging unhelpful thoughts, you may be able to stop ruminative thought patterns (the racing mind) that keep you awake at night.

Sophie Bostock, PhD is a leading expert and speaker in the field of sleep science. She studied medicine at Nottingham University, followed by an MSc in Entrepreneurship. After several years in consulting, she completed a PhD in Health Psychology at University College London (UCL), investigating why happiness protects against heart disease.