Reaction times are as bad as when under the influence of alcohol
We all know the feeling: after a short night, we're tired and less focused. If this lack of sleep extends over a longer period, it has measurable consequences for the body.
Sleep deprivation has a similar effect on our reaction times as alcohol. After 24 hours without sleep, participants in a study displayed, on average, similar reactions to people with a blood alcohol level of one part per thousand . There are however exceptions: some people are less sensitive to little sleep and their abilities are hardly affected.
Psychological consequences of sleep deprivation
In addition to reaction times and decision-making behaviour, insufficient sleep also affects the mind in other ways: memory skills worsen, and we quickly become irritable and unfocused. Depression is also closely linked to lack of sleep. In other words, a sleep deficit can trigger depressive moods. In turn, sufferers of depression often sleep poorly – a vicious cycle.
Can we make up for a lack of sleep at the weekend?
Many experts recommend a regular sleep pattern, especially when it comes to getting up. Consequently, insufficient sleep can't be compensated for at the weekend. A recent and much-cited study had little to add to this. The study merely concluded that people who make up for a lack of sleep at the weekend are, at least, not likely to die earlier. However, what wasn't recorded were the test subjects’ everyday concentration and performance levels. In other words, the fact remains that insufficient sleep over a long period of time is unhealthy and can't be compensated for.
Sleep deprivation affects gene activity
What many people don't know is that our genes work our whole life long. The body depends on gene activity, known as gene expression, as it performs functions such as cell regeneration, for example. Sleep also affects gene expression, according to a group of researchers at the University of Surrey.
When participants in a study slept barely six hours for a week, their gene expression was disturbed. This disturbance affects the hormones that are released on a 24-hour basis, thereby bringing the human body's «inner clock» into disarray. It is assumed that this inhibits cells throughout the body from regenerating properly, weakens the immune system and makes it harder for the body to compensate for stress.
Sleep deprivation raises blood sugar levels
Research suggests that a lack of sleep influences a person’s glucose tolerance. According to these studies, people who sleep less than six hours have higher blood sugar levels. After one week of sleep deprivation, some study participants already had a metabolic condition similar to that of a diabetic.
It can be seen that not getting enough sleep has a whole range of consequences that are directly associated with the sleep deficit. The consequences of sleep deprivation also lead to long-term illnesses. When a group of researchers from the US put together the results of a number of studies, one conclusion was that a chronic sleep deficit increases the risk of diabetes mellitus and cardiovascular diseases. Large-scale studies like this clearly show that people who don’t get enough sleep are more likely to die earlier. However, the problem with such studies is that there is also a section of the population that are less sensitive to insufficient sleep. The studies therefore merely show a tendency, but cannot speak for the individual.
Varies from person to person
Expert opinion says that people react very differently to insufficient sleep. There are some who react extremely sensitively and can barely concentrate when suffering from sleep deprivation, while others notice only minimal cognitive deficits. According to Serge Brand, psychologist and sleep researcher at UPK Basel, «the decisive factor is not so much the duration of sleep, but the subjectively perceived quality of sleep». Also worth mentioning is that sleep quality is closely related to a person’s sleeping pattern and phases.
Are people divided into morning and evening types?
The classic division between morning and evening types – early birds and night owls – does indeed exist. While night owls reluctantly heave themselves out of bed at six in the morning, early birds are already up and running. According to German sleep researcher Jürgen Zulley, only around 15 percent of the population are clearly one or the other. The rest of us fall into the broad middle range of normal sleepers. According to Zulley, it’s our genes that determine whether we live our lives as night owls or early birds.
Our sleep requirements change with age
Just as each person’s need for sleep is highly individual, it changes dramatically during the course of our life too. While newborn babies sleep for around 16 hours a day, children aged between five and ten need around nine to eleven hours’ sleep. As we age, the length of time we sleep drops continually. For this reason, seventy-year-olds who wake up after six or even just five hours’ sleep do not normally need to be concerned.