New research has found that too much or too little could be harmful.

The amount of hours you spend asleep isn’t the be-all end-all when it comes to health: one study found that sleep regularity was more strongly linked to a longer life than sleep duration.

But that’s not to say it doesn’t matter. Getting at least seven hours’ shut-eye nightly seems to help us live longer, function better, and even lower our dementia risk. 

And the lead author of recent research published in Nature, Junhao Wen, has said: “Previous studies have found that sleep is largely linked to ageing and the pathological burden of the brain.

“Our study goes further and shows that too little and too much sleep are associated with faster ageing in nearly every organ, supporting the idea that sleep is important in maintaining organ health within a coordinated brain-body network, including metabolic balance, and a healthy immune system.” 

Using data collected from half a million members of the UK Biobank (a depositary of thousands of participants’ health data that scientists can use for health research), Wen created 23 “ageing clocks” to predict the rate of ageing of various organs and body systems. 

He then compared that to the participants’ sleep patterns.

The paper said that those who sleep less than six hours or more than eight hours a night saw faster ageing, on average: a “U-shaped” association.

And there appeared to be a sleep duration sweet spot, too. 

The least amount of ageing seemed to happen in those who slept between 6.4 and 7.8 hours a night in this research, though this varied by “organ and sex in the UK Biobank (aged 37-84 years)”.

And people who neither slept too much nor too little seemed to be at a lower risk of “all-cause mortality”, too. 

In this research, either too much or too little sleep was linked to a higher likelihood of disease. 

Short sleep was linked to depression, anxiety, type 2 diabetes, hypertension, ischemic heart disease, and heart arrhythmia. 

Both short and long sleep were associated with chronic obstructive pulmonary disease, asthma, and multiple digestive issues, including gastritis and gastroesophageal reflux disease (GERD). 

“The broad brain-body pattern is important because it tells us that sleep duration is a deeply embedded part of our entire physiology, with far-reaching implications across the body,” said Wen. 

The paper read, “Our results underscore the systemic biological adverse associations of disturbed sleep and provide a compelling framework for more targeted and thoughtful attention to sleep disturbance as a potential signal of emerging health issues and a partner in the quest to promote healthy ageing, reduce disease risk and extend lifespan.”