Sleep is a simple tool with incredibly powerful benefits. In our culture of celebrating busyness and a need to fit it all in, we can be quick to dismiss our need for a good night’s sleep. But, research shows that a good night’s sleep truly is vital for our health. Sleep is probably the most under-utilised tool for wellbeing. The good news is that focusing on good quality sleep is often one of the easiest ways to quickly improve your mental and physical health. Getting into bed a little earlier and getting that quality sleep sounds simple, and it has a huge number of health benefits.
What happens when we sleep?
Throughout the night we experience various stages of sleep, one stage of rapid eye movement (REM) sleep and three stages of non-REM (NREM) sleep, and we cycle repeatedly through these different stages throughout the night. Each stage of sleep has a distinctive function:
Non-REM sleep plays a central role in the growth and repair of our bones and tissues.
REM sleep is when most of our psychological and emotional repair occurs, such as stress and memory processing.
Hence, sleep has wide-ranging impacts and affects all aspects of our health: the mental, emotional, and physical.
Sleep and our mental health
In essence, sleep helps us to wake up happy and feel ready for the day ahead. In the short-term, this is because sleep deprivation knocks out the prefrontal cortex, the area of the brain that helps to regulate emotions and pushes us into our threat-detecting part of the brain, the amygdala, meaning we tend to view the world around us and ourselves more negatively.
In terms of the impact on our long-term mental health, sleep helps us diffuse the stresses that we’ve experienced in the day, helping to reset our emotional balance the next day. As a result, if you’re not getting enough good quality sleep, your risk of experiencing poor mental health is increased.
Brain scans show a rise in the reactivity of the amygdala – a key spot for triggering anger and rage – in those who were sleep-deprived. A growing body of research indicates that sleep deprivation is a strong predictor of mood disorders in general, including anxiety or depression. In one study, people with chronic insomnia were five times more likely to develop depression and twenty times more likely to develop a panic disorder.
On the positive flipside of this, research has shown that any improvement in our sleep can help to improve our mental health.
Sleep and our physical health
Sleep is fundamental to helping us boost our immunity by helping to produce antibodies that protect us against viruses and pathogens; so, getting a good night of sleep can protect us from getting coughs and colds. A lack of sleep also impacts the effectiveness of our natural killer cells, which are critical for warding off many of the diseases mentioned above. Walker’s studies have shown that after just one night of only four or five hours of sleep, your natural killer cells – which attack the cancer cells that can appear in your body every day – drop by up to 70%.
Getting enough sleep is important for our heart health, by helping to lower our blood pressure and regulate our heart rate. Studies show a clear correlation between sleep deprivation and other common diseases. Adults aged 45 years or older who sleep less than six hours a night are, for example, up to 200% more likely to have a heart attack or stroke in their lifetime, compared with those sleeping seven or eight hours a night. This is in part because even just one night of sleep reduction can speed up your heart and increase blood pressure.
Sleep is also the time when the lymphatic system in our brain, which flushes out the neurotoxins that have built up in the day as a product of thinking, is at its most active. In the long-term, adequate washing out of toxins, facilitated by good quality sleep, can protect us against Dementia and Alzheimer’s.
We also see the impact of our control on other aspects of our health, including blood sugar control and weight gain. Studies show that a lack of sleep reduces our insulin response, the hormone that regulates our blood sugar levels (hence the link to diabetes), while also reducing our levels of leptin, the hormone that controls our satiety levels, and increasing our hunger signalling hormone, ghrelin.
How much should we be sleeping?
Most of us aren’t getting enough sleep now. On average, the amount we sleep has decreased by 15-20% over the last hundred years. In the UK we’re averaging 6 hours and 49 minutes per night, and in the US it’s just 6 hours and 32 minutes. The optimal range is between 7-9 hours per night, with 8 being the average. Research shows that for most of us, any lower than 7 hours a night can be bad for our health.
Our biological need for sleep is determined by our genetics. About 80% of us need about 7 to 8 hours of sleep each night, and 97% of us require between 6 and 9 hours of sleep. A few good pointers to help you figure out whether you’re getting enough sleep is to check in with whether you wake up feeling refreshed, whether you’re able to go about your day with stable emotions, and whether you’re able to cope with what the day brings.
In short, the benefits of good sleep can impact every moment of our day by making us feel more emotionally and physically resilient and healthy. Achieving enough good quality can at times feel challenging, and it’s completely normal to go through waves of life where you feel like you’re able to prioritise sleep more than at other times. But from our conversation with Dr Guy Meadows for season 7 of the podcast, the important message to take home is that any improvement in the regularity and quality of our sleep is one of the simplest and most powerful behaviours we can do to improve our overall health and feelings of wellbeing.