The biology of sleep
According to the American Time Use Survey, on average, a person aged 25-54 who is employed and has children will spend 32-36% of their day asleep. When they're not sleeping they spend:
- 37% of their day working
- 10.5% of their day doing leisure and sport activities
- 5% of their day doing household work
- 4.2% of their day eating and drinking and
- 6.6% of their day doing other activities
During sleep, critical and complex processes take place involving multiple structures in the brain. These processes include memory consolidation, processing information, and emotional processing. Sleep even promotes problem solving abilities.
With so many processes depending on sleep, it comes as no surprise that the quality of our sleep can define our performance while awake. In turn, sleep quality is influenced by the timing and duration of our sleep, which in turn is determined by the interplay between circadian timing, sleep pressure and societal pressures. For example light detection by the eye influences circadian timing, which is why the drive for wakefulness increases in morning. Likewise, pressure to sleep is driven by the time spent awake and vice versa and finally, societal activities, like the consumption of caffeine can disrupt sleep, as caffeine blocks receptors that mediate sleep pressure.
Consequences of sleep disruption
With sleep playing such a profound role in biological process it should come as no surprise that disruption to sleep and circadian rhythm would have profound effects. For example, short term sleep disruption can lead to loss of attention, high levels of micro-sleeps, failure to process information, memory impairment, and reduced cognition and creativity. Longer term disruption on the other hand can include immune suppression, increased risk for infection and cancer, increased risk of cardiovascular disease and diabetes, and increased propensity for stimulant use. There is also a link to increased vulnerability to mental illness including anxiety, paranoia, and exacerbation of symptoms in those with bipolar disorder and schizophrenia.
Russell says that just in the US approximately 100,000 traffic collisions every year occur in relation to sleepiness, many of which are caused by microsleep. There is a similar association with air accidents.
If left untreated, sleepiness due to OSA can severely impair driving, with affected drivers being three to nine times likelier of being in an accident. Accidents are also likely to be more severe due to failure to correct errors quickly, with accidents involving HGVs tending to be particularly serious.
Insomnia is a common disorder. It is estimated that 30% of the population regularly experience symptoms as such difficulty in falling or staying asleep and early awakening and 10-12% of the population is affected by chronic (long-term) insomnia. During the daytime, symptoms can include fatigue, low mood, poor concentration and reduced productivity. Insomnia is also considered the most common expression of mental ill health and a risk factor for illnesses.
Despite its prevalence, insomnia is generally poorly managed in clinical practice. In fact it is often trivialised, with patients often encouraged to treat their symptoms with a plethora of marketed 'treatments' that have not been validated in clinical studies and do not work. These include wrist bands, special beds, mattresses and pillows, crystals, magnets and homeopathies, aromatherapies, pseudo-neuroscientific practices, sleep apps, and over-the-counter products.
Within this cacophony of false remedies, some evidence based approaches to treat insomnia are being developed. Furthermore, some of these approaches can be scaled up to be delivered at a population level. The first such approach that comes to mind is medications, which are affordable, evidence-based (to an extent), and can be standardised and indeed NHS England issues twelve to 14 million prescriptions for sleeping tablets each year. However medications have limited effectiveness, which is why the recommended first line of treatment is often Cognitive Behavioural Therapy for Insomnia (CBT-I). This type of therapy has been endorsed in practice guidelines from the American College of Physicians and in a European guideline. Patients who do not respond to CBT-I are then prescribed pharmacological solutions.
CBT-I is effective and offers a choice of evidence-based treatment to all patients. This means we might soon be seeing clinical guidelines suggesting CBT-I be offered as a first line treatment for insomnia. Implementation and commissioning pathways in the NHS are already being developed, with Sleepio available in London, Oxfordshire, Buckinghamshire and Berkshire, through implementation funded from Innovate UK and NHSE initiatives.
Still there is a need to regulate digital medicine. The non-profit organisation Digital Therapeutics Alliance was established in 2017 and is working to optimise and integrate digital therapeutic solutions into healthcare to improve health outcomes. It is important that developers of such technologies undertake appropriate research including pre-registered trials, subject to thorough analysis and independent scrutiny to ensure that the public is well served.