Levels of the beta amyloid protein naturally rise and fall over 24 hours in both mice and people. However, the protein forms permanent plaques in Alzheimer's disease.
Experiments at Washington University showed that nocturnal mice slept for 40 minutes during every hour of daylight. However, as soon brain plaques started to form the mice were sleeping for only 30 minutes.
One of the researchers, Prof David Holtzman, said: "If sleep abnormalities begin this early in the course of human Alzheimer's disease, those changes could provide us with an easily detectable sign of [the disease]."
"If these sleep problems exist, we don't yet know exactly what form they take, reduced sleep overall or trouble staying asleep or something else entirely."
However, findings in mice do not always apply to people as there are many reasons for disrupted sleep.