We all recognise the spaced-out feeling of a missed night’s sleep. It can make us groggy and leave us unable to think straight. But just how long can you go without sleep?
Why Do We Need Sleep Anyway?
It might sound like a silly question, but when we think about sleep in evolutionary terms, we quickly realise it carries some serious drawbacks.
Sleep leaves us unconscious and vulnerable for several hours at a time. For animals out in the wild, sleep increases the risk of being ambushed and killed.
So, if it were possible for evolution to get rid of sleep, it seems an obvious thing to give up. So why do we sleep?
Research in this area is still pretty new, but scientists believe sleep might help our brains make adjustments, to renew and repair connections, and for our bodies to generally heal.
While it isn’t direct evidence of what sleep does for us, an interesting way of understanding sleep’s importance is to see how a lack of sleep impacts us.
What Happens When We Go Without Sleep?
In otherwise healthy adults, a few days of interrupted sleep or even full sleeplessness is unlikely to lead to serious health problems, but going without sleep does have an impact.
Side-effects of sleeplessness can include:
- Memory impairment
- Reduced coordination
- Reduced reasoning skills
- An increase in the likelihood of mood problems
Researchers are also interested in studying the long-term effects sleeplessness can have on our bodies.
The Problem of Testing Sleep Deprivation in Humans
Purposefully depriving someone of sleep is classed as torture and is against various human rights laws monitored by the United Nations.
As such, scientists can’t (and rightly won’t) subject people to long-term sleep deprivation. This means getting a definitive answer on how long we can survive without sleep isn’t easy.
We know that depriving animals of sleep for an extended length of time has serious, often lethal, consequences. For example, a 1995 study of rats deprived of sleep for two weeks showed serious metabolic problems. Within four weeks, the rats died.
Still, there are cases of people choosing to stay awake for long periods of time, and the results are fascinating.
Lasting Nearly Two Weeks Without Sleep
As the BBC reports, there is the now-famous case of Randy Gardner.
In 1963, 17-year-old Gardner, together with his friend Bruce McAllister, devised a science fair project that, if successful, wouldn’t just wow their classmates but would break a world record: They would stay awake longer than anyone else in the world.
At the time, the world record was held by a man from Honolulu who had managed to stay awake for 260 consecutive hours.
The pair enlisted the help of researcher William Dement of Stamford University. Despite symptoms like loss of coordination, memory problems, and even hallucinations, Randy broke the world record, going 264 hours or about 11 days without sleep.
Interestingly, Gardner appeared to suffer no long-lasting effects from his sleep deprivation experiment. In fact, within a few days of ending the experiment, and a lot of sleep, he was back in school apparently no worse off.
The story doesn’t end there though. While Gardner seemed to suffer no health complications at the time, in later life Gardner reported years of insomnia. We don’t know if his earlier sleep experiment contributed to this problem, but it is an interesting addition to the story.
Nevertheless, Randy Gardner was a physically fit teenager and his sleep experiment probably shows us the upper limits of how long most people can go without sleep and remain healthy.
However, there are some rare cases where people have, unfortunately, developed conditions leading to prolonged sleepless nights, and the impact is devastating.
Rare Genetic Conditions Show Sleep Deprivation Effects
Among a range of health problems that can cause sleep deprivation, there is a condition known as Fatal Familial Insomnia or FFI.
FFI impacts the part of our brain that controls our sleep cycle. Symptoms usually first show up when the person with this genetic difference is around 40-60 years old. The condition has many symptoms but a key problem is chronic sleep disturbance.
Typically, people with Fatal Familial Insomnia will develop issues such as heart problems and a greater chance of picking up infections. Usually, sufferers will die within six to 36 months of first showing symptoms.
While FFI is an extremely rare genetic disorder, it shows how much the body relies on consistent sleep and how, when our sleep is severely compromised for long periods of time, it is bad for our health and even dangerous.
Scientists still don’t have a definitive answer to how long we can go without sleep, but as Randy Gardner’s story shows, it’s possible to last around 11 days without sleep. Any longer than that and the risk of serious health problems seems extremely high.
What is clear from the research we do have is just how critical sleep is to not just our survival, but to our living an enjoyable life with a good working memory and stable mood.
So it’s important we don’t think of sleep as an afterthought, but that we put sleep right at the heart of our health and wellness routines along with exercise and eating right.
Do you have experience of sleeplessness? How did you fight it? Let us know in the comments below.