Owls and Larks

Some people have a natural preference for sleeping late or early and are commonly known as owls and larks.  People also often describe themselves as being a morning or evening person.  This natural variation is not just a personal preference but is actually genetically determined, it is part of the normal variation in people’s sleep needs.  At the extremes this variation can become a disorder that is very disruptive to life – delayed sleep phase syndrome/disorder, or advanced sleep phase syndrome.

Apart from the disorders of sleep phase, which require specialist treatment, it is useful to notice that whether someone is naturally an owl or a lark will contribute to how well they adapt to different occupational routines, for instance people with an evening preference found it easier to tolerate shift work than morning people (1).  Someone’s natural sleep timing preference will also affect at what times of day they perform at their best, and might affect when it is best for them to plan to do certain activities.

It can be useful to acknowledge that the sleep pattern that is natural for one person, can be quite a challenge for another, and that difficulty with early starts is not equivalent to laziness (2).  Whilst it is often necessary for people to adapt to social norms regarding sleep times, sometimes it is suggested that their routine adapts to match their ideal sleep schedule – there has been some research recently for instance on altering the times of school days to suit adolescents who tend to have a more delayed sleep phase on average (3 & 4).


1) Saksvik, I.B., Bjorvatn, B., Hetland, H., Sandal, G.M. & Pallesen, S., 2011. Individual differences in tolerance to shift work–a systematic review. Sleep medicine reviews, 15(4), pp.221–35. http://www.smrv-journal.com/article/S1087-0792(10)00068-7/abstract

2) Barnett, D., 2015. Start school day at 11am to let students sleep in, says expert. The Guardian.

3) Kelley, P., Lockley, S., Foster, R.G. & Kelley, J., 2015. Synchronizing education to adolescent biology: “let teens sleep, start school later.” Learning, Media and Technology, 40(2), pp.210–126. http://www.tandfonline.com/doi/pdf/10.1080/17439884.2014.942666

4) (Website) Division of Sleep Medicine, Harvard Medical School, 2007. Individual Variation and the Genetics of Sleep. Healthy Sleep. available at: http://healthysleep.med.harvard.edu/healthy/science/variations/individual-variation-genetics

Content on this page contributed primarily by Sophie Faulkner.
Last updated June 2016.