你每天平均睡多长时间？八小时通常被认为是 “黄金” 睡眠时间，但这是否因人而异？哪些因素决定一个人究竟该睡多久才好？

Charles Darwin once said "A man who dares to waste one hour of time has not discovered the value of life". If you live one hundred years, that only equates to twelve-hundred months – and when you break it down even further into days, hours and minutes, it gets more frightening. Why is this relevant? Well, quite simply put: life is short. Spending eight hours every day in a slumber means you're losing a third of your life to bed. So, the question is: is eight hours the exact amount we need, or is it just a myth?

While most scientists agree that between seven and nine hours a night is the optimal amount, this is just a rough estimate. In truth, it's a little more complicated than that. It seems that the amount of sleep you need depends upon your age – with infants needing much more than adults. What does seem apparent is that around seven and a half hours' sleep is a good amount. In a study conducted at the University of Surrey Sleep Research Centre, the effects of sleep were monitored.

One group slept for six and a half and the other for seven and a half hours per night. While some findings were predictable – irritation and lower concentration in the group who slept less, there were some more surprising findings. The genes of people who had less sleep were affected. Genes associated with inflammation, the immune system and stress response became more active. The team also observed increases in the activity of genes related to diabetes and risk of cancer. 

One of the biggest issues is that myths regarding sleep are constantly perpetuated. For example, have you ever heard that you can train yourself to need less or no sleep? It's simply not true. We will always need a certain amount of sleep – eight hours might not be the exact sweet spot, and there are factors like age to take into consideration, but one thing is true – there is a certain amount we do actually need.