Sleep and attention: what short nights do to your focus

§ 1What sleep loss does to attention

Lim and Dinges (2010) combined 70 studies of short-term sleep deprivation. Of all the abilities measured, simple attention, such as responding quickly to a signal, was affected most, with a large effect (g = −0.78). Complex reasoning was affected less. The typical sign is not a general slowing but lapses: moments when a response comes very late or not at all.

This is why sleep researchers use the psychomotor vigilance task, a simple reaction task with random waits. It is very sensitive to sleep loss and changes little with practice (Basner and Dinges, 2011).

§ 2Short nights add up

In a laboratory study by Van Dongen and colleagues (2003), people who slept six hours a night for two weeks showed steadily growing deficits on the vigilance task. Their own ratings of sleepiness rose much less. After a run of short nights, you may feel fine while your attention is not.

§ 3How much sleep adults need

A consensus statement of the American Academy of Sleep Medicine and the Sleep Research Society recommends that adults sleep seven or more hours per night on a regular basis (Watson and colleagues, 2015). Needs vary between people, but regularly sleeping less is linked with poorer attention and health.

§ 4Time of day matters too

Attention also rises and falls over the day. Performance depends on your body clock and on whether a task falls at a time that suits you: morning types tend to do better in the morning and evening types later in the day (Schmidt and colleagues, 2007). Alertness often dips in the early afternoon as well. This is one reason to compare test results taken at a similar time of day, and to avoid reading much into one result taken at an unusual hour.

§ 5What helps

• Give yourself enough time in bed, regularly, rather than catching up only at weekends.
• Plan demanding work for the time of day when you are usually most alert.
• Caffeine can mask some effects of sleepiness for a while, but it does not replace sleep.
• Take short breaks during long, monotonous tasks: attention declines with time on task, and micro-breaks can reduce fatigue (Albulescu and colleagues, 2022).
• If you are often sleepy during the day despite enough time in bed, talk to a doctor.

§ 6Seeing it in your own results

A simple self-experiment: do the same short reaction test on several mornings, at a similar time, and note how long you slept. Over a few weeks you may see a pattern in your own data. It will be noisy, and it is a pattern in your results, not a sleep assessment or a diagnosis.

Questions and answers

Does one bad night affect attention?

Yes. Even one night of sleep loss increases attention lapses, and sustained attention is affected more than other mental abilities.

Can coffee make up for lost sleep?

Caffeine can hide some effects for a while, but it does not restore what sleep does.

How many hours should adults sleep?

Seven or more hours a night on a regular basis, according to a consensus statement of sleep medicine organisations.

Can an app tell me if I have a sleep problem?

No. An app can show patterns in your own results, but only a qualified health professional can assess sleep problems.