The Guardian: Embracing our individual sleeping patterns could be the key to a better night’s rest.

What we can be sure of is that sleep is critical for good health. It helps us form memories and solve problems, allows tissue growth and repair, promotes metabolic health and removes toxins from the brain, including amyloid beta which is linked to Alzheimer’s disease. Insufficient and disrupted sleep is now known to result in altered emotional responses such as irritability, anxiety, loss of empathy, impulsivity and a reduced sense of humour. Cognitive performance also takes a hit, leading to a loss of attention, concentration, communication, decision making, creativity, and the ability to multitask. Finally, poor sleep affects physiological health, leading to an increased risk of stroke, heart attack, infection, cancer, obesity, type 2 diabetes and mental illness. Hopefully this encyclopedic list will convince you that insufficient sleep is so much more than the inconvenience of feeling tired at the wrong time. It should also prompt the question: so what is “good sleep”?

We are regularly told that the “ideal” night of sleep consists of eight uninterrupted hours. But this belief is wrong in so many ways. Sleep is like shoe size. One size does not fit all, and these kinds of edicts cause confusion and anxiety for many. The truth is that how long we sleep, our preferred sleep times and how many times we wake during the night vary both between people and in the same person as they get older.

Most young and middle aged people (18 to 64 years) sleep between seven and nine hours each night, but some perfectly healthy individuals may sleep six or even 11 hours. After 64, the average amount of sleep is between seven and eight hours, but the full range can be between five and nine hours. So, sleep shortens as we age. We see the same variety with sleep timing. Your “chronotype” refers to whether you are a “lark” (10% of the population), “owl” (25% of the population), or in between (sometimes called “dove”, representing most of us, at 65% of the population). This is greatly influenced by your biological (circadian) clock. But these clocks change with age. As teenagers and young adults, people tend to have later chronotypes, then move earlier in their middle and older years.

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