The battle to boost our deep sleep – and help stop dementia

The biological brainwashing' that happens while you are sleeping is crucial for filtering out toxins. Here's how to optimise your overnight cycle

Tonight, and almost every night, something amazing will happen inside your brain. As you turn off the light switch and fall asleep, you will be switching on the neurological equivalent of a dishwasher deep-clean cycle. First, the activity of billions of brain cells will begin to synchronise, and oscillate between bursts of excitation and rest. Coupled with these slow waves", blood will begin to flow in and out of your brain, allowing pulses of the straw-coloured cerebrospinal fluid (CSF) that usually surrounds your brain to wash in and be pushed through the brain tissue, carrying the day's molecular detritus away as it leaves.

Most people recognise that if they don't get enough sleep, their mood and memory will suffer the next day. But mounting evidence is implicating this brainwashing" function of sleep in longer-term brain health.