Fatigue: The Facts

Fatigue is the subjective feeling of the need to sleep, an increased physiological drive to fall asleep and a state of decreased alertness.

Most adults require 7 to 8 hours of restorative sleep each night. Restorative sleep needs to be uninterrupted.

A sleep debt occurs after restricted sleep for 2 or more nights.

Moderate sleep restriction to 6 hours per night for 2 weeks impairs performance equivalent to 1 night of complete deprivation.

Cognitive function is impaired after 16 to 18 hours of wakefulness.

20 hours of wakefulness can cause impaired performance equivalent to being over the UK driving limit for alcohol.

Age impairs recovery from sleep loss and alters sleep patterns.

Fatigue induces sleep lapses, also known as microsleeps, which are spontaneous and uncontrolled and often go unrecognised.

Two consecutive nights of restorative sleep are needed to recover from sleep loss.