Students are often seen as an anti-role model of sleeping habits. Indeed, our daily routines are hugely chaotic: schedules change every few weeks, deadlines or parties demand late-night shifts, weekends invite sleep-ins or adventurous trips. So it is not without reason that people think of us as one of the most sleep-deprived age groups in society. In 2008, a scientific study provided the evidence: more than one third of the 313 student participants experienced sleeping problems that may interfere with daily performance.
On the internet there is plenty advice for a healthy sleeping life: eight hours every night, regular bedtimes, no late-night food, work, intense sport or alcohol. The aim is to establish a routine of one hour of relaxing before we go to sleep. But is all that really necessary? To find out, I visited the psychologist Annemiek Vermeeren, an expert on sleep and sleeping disorders.
My first question is related to quality. What is the most important condition to achieve high-quality sleep? Regularity and duration matter most, Vermeeren says. There are two processes that influence our sleep-wake pattern. The first is our homeostatic sleep drive: the longer we are awake, the more it increases. Second: our body’s internal clock or the so-called circadian rhythm. This clock is monitored by a specialised centre in our brain, the suprachiasmatic nucleus of the hypothalamus. This is directly linked to the retina in our eyes, and thus knows whether it is dark or bright outside. Even though it is as tiny as a grain of rice, it coordinates many important functions in our bodies and keeps them in an approximately 24-hour rhythm. Without it, we could not maintain our daily pattern of sleep; but this small centre deep inside our brain also regulates the daily rhythm of our body temperature, immune system and digestive activity.
What does it mean for our sleeping lives as students? Even if we skip a whole night of sleep, we do not have to make up for the entire seven or eight hours we have missed. Our sleep drive gets rebooted during deep sleep, so all we have to do is make sure that the first hours of sleep in particular do not get interrupted. An extreme illustration is the self-experiment by Randy Gardner in 1964. He deprived himself of eleven nights of sleep – which caused mood swings, loss of concentration, short temper, problems with short-term memory, paranoia and hallucinations – but he needed only two (long) nights of sleep (of fourteen and ten hours) to completely recover.
For regular and high-quality sleep our internal clock and our sleep drive need to work together to signal the need for sleep and establish the bodily state that enables us to actually fall asleep. As a result, any disturbance to our internal clock, through a chaotic sleep and activity pattern, compromises our sleep quality. More importantly, our internal clock is not only in charge of our ‘sleep department’, but is also involved in coordinating our digestive and immune systems. The advice not to eat, do intense sport or engage in other stressful activities before going to sleep thus makes sense: all these systems are interlinked in the body.
What about the 8-hours-every-night rule? Does it apply to everyone? No, according to Vermeeren. Everyone has to find his or her own golden number of hours. Age has a great influence on the need for sleep, but there are large individual differences, and it also depends on the overall state of our body. And duration is important, but as Vermeeren stresses, so is quality. “High-quality sleep means enough deep sleep, and deep sleep is affected by, for example, alcohol.” So sleeping eight hours after drinking a bottle of wine can be less beneficial than sleeping five, sober.
What would be Vermeeren’s sleep advice to students, then? “Stick to regular bedtimes throughout the entire week to minimise disturbances, and establish a comfortable sleeping environment. Everything else should follow naturally.”