Just one night of poor sleep is enough to trigger a spike in a brain chemical linked to Alzheimer’s disease, a new study has shown.

Although scientists knew there was a link between dementia and lack of sleep, it was unclear whether the disease was driving insomnia or vice versa.

Now researchers at Stanford University and Washington Medical School have discovered that even a single night of disrupted sleep is enough to raise levels of amyloid beta - a substance which can clump together and stop brain cells communicating with each other.

Although the levels returned to normal, scientists fear that continued sleep deprivation could allow an unhealthy build-up of brain plaque which eventually kills off neurons and wipes memory.