I feel great on 7 hours of sleep but like a zombie after 8 — two doctors explain why, and how much sleep is enough

The image shows a dark haired woman wearing stripy pyjamas in bed squinting into the sunlight as she turns off her alarm clock.

We’ve long been told that eight hours of sleep is the golden rule. Whether it’s boosting your physical recovery or keeping your mental health in tip-top condition, eight hours of sleep has historically been cited as a good benchmark to aim for.

But how true, and realistic, is that rule? With our busy schedules and hectic lifestyles, squeezing in eight hours of sleep isn’t always possible, especially for mothers, shift workers and carers.