Friday, March 16, World Sleep Day is a little reminder to us all to try to get some much-needed shut-eye. Here we round up some recent studies which show how important sleep is for good health.

Reduced risk of obesity

Various studies have linked a lack of sleep to an increased body mass index (BMI) and risk of obesity. A study published last year found that children who slept longer had lower Body Mass Index (BMI) scores than those who slept less, and for every hour later that a child goes to bed, their BMI score also increases by a small amount. A UK study which looked at the effect of sleep deprivation in adults also found that the waist measurements of people who slept on average six hours per night were three centimeters higher than those who slept nine hours a night, and these participants also had more chance of being overweight.

Reduced risk of Alzheimer's disease

A lack of sleep is increasingly found to be a risk factor for developing Alzheimer's disease and other forms of dementia. One US study found that those who reported worse sleep quality, more sleep problems and daytime sleepiness had more biological markers for Alzheimer's disease in their spinal fluid than people who did not have sleep problems. A 2015 study also demonstrated the importance of sleep in keeping the brain healthy when it found that sleeping on the side, rather than on the back or front, opens a passage in the brain called the glymphatic pathway. Opening this pathway bathes the brain with cleansing cerebrospinal fluids (CSF) and interstitial fluid (ISF) and flushes out amyloid β and tau proteins, a buildup of which are found in the brains of those with Alzheimer's disease.

Reduced risk of depression

As with dementia, there is increasing evidence to suggest that sleep could be a large factor in developing depression and other mental health disorders. A US study found that less than 8 hours sleep a night, or taking longer to fall asleep, is linked to negative, intrusive and repetitive thoughts like those seen in anxiety and depression. UK research published last year in The Lancet also suggested that treating insomnia and sleep problems could be an important first step to take to also help treat mental health problems such as anxiety, depression, and paranoia.

Reduced risk of gestational diabetes

A large-scale meta-analysis published last year found a link between a lack of sleep during pregnancy and an increased risk of gestational diabetes. After looking at eight studies which included 17,308 pregnant women, the researchers found that an average of less than 6 hours sleep a night was associated with a 1.7 fold increase in the risk of being diagnosed with gestational diabetes. In addition, in one study where sleep was measured objectively, rather than self-reported by the women, those who slept less than 6.25 hours per night had a 2.84 fold increase in risk of having the condition compared to women who slept more than 6.25 hours per night.