It has been shown that most people are either ‘Night Owls’, who describe themselves as naturally more active and alert in the evening, or ‘Morning Larks’, who wake early and become less alert once daylight decreases. These patterns are linked to changes in the levels of the hormone melatonin (which is associated with feelings of sleepiness). Those who follow a ‘Morning Lark’ pattern show high levels of melatonin early in the evening and low levels by the early morning, with the opposite being true in ‘Night Owls’ with higher levels of melatonin still present in the morning after waking. Therefore employers should allow for flexible working hours to accommodate people’s sleep patterns