Sleep loss hampers performance

One night of good sleep is not enough to stay alert and attentive. Many nights of too little sleep when the body's rhythm says it is time to snooze have cumulative detrimental effects on how a person performs and could be a safety risk.

Insufficient sleep over multiple sleep-wake cycles causes performance to deteriorate much faster for every additional hour we spend awake, particularly during the biological night. On average, a person needs about eight hours a night to preserve performance. Acute sleep loss is being awake for more than 24 hours in a row and chronic sleep loss is getting only about four to seven hours of sleep per night.

Researchers from America tracked nine healthy volunteers - five men and four women - to see what effect a combination of acute sleep loss, chronic sleep loss and biological sleep rhythm might have on their ability to function. The volunteers were kept in a hospital for 38 days and lived on various sleep cycles. They were tested every four hours to measure alertness and attentiveness.

It was found that while most participants caught up on acute sleep loss with a single night of 10 hours sleep, those with chronic sleep loss showed deteriorating performance for each hour spent awake.

It has been known that three days is not enough to recover from chronic sleep loss, but it is still not known how many days or weeks may be needed. People may not realise that they have a chronic sleep debt because it slowly builds over weeks.

People may be largely unaware that they are chronically sleep-deprived. It's when they then stay up and try to pull an all-nighter that they are much more vulnerable to sudden sleepiness, inattentiveness and potentially accidents and errors.