If you’re anything like me, then you will be familiar with Monday-itis. It’s a terrible affliction, with symptoms usually presenting at the start of the working week. You feel tired and flat and you have to drag yourself out of bed. While you might think that motivation is the issue because you don’t want your weekend to be over, it turns out that you may actually be suffering from something called “social jet lag,” and it has a lot to do with your sleep.

I recently spoke with Professor Till Roenneberg from Ludwig-Maximilian University in Munich who is a sleep expert, specialising in chronobiology – the study of our biological rhythms. (Listen to the podcast in iTunes or at the end of this blog post.) His research, which draws on data collected from more than 55,000 people, shows that each of us has a different chronotype, or timing of our biological clock. You may be an early-bird “lark” who prefers going to bed and getting up early, you may be a night “owl” who prefers late nights and late mornings, or you may be like the majority of people and perch somewhere in the middle.

It’s estimated that only about 10 percent of us are morning larks, and roughly 20 percent of us are night owls, which has led Roenneberg to conclude that many of us are suffering from a kind of “social jet lag.” “We find that the timing that our biology wants us to live is completely in a different time zone than the time that our social obligations want us to live,” says Roenneberg. In other words, that Monday morning jet lag feeling may be because your Monday to Friday work-week routine is forcing you to live in a time zone which is not natural to you biological rhythm.

Where you roost on the lark-to-owl scale depends on a number of things including your genetics, when the sun rises and sets in your day, your age, and your gender. Your chronotype can also shift throughout your lifespan. For example, as you age, the tendency to prefer waking earlier increases. On the other hand, teenagers tend to be night owls.

With a growing body of research illuminating the link between poor sleep and poor health, researchers like Roenneberg are starting to investigate whether being forced to operate on a social clock that is counterproductive to your natural rhythms might be harming your health. For example, night owls are more prone to depression and more inclined toward substance abuse, possibly because they rely on uppers and downers (such as caffeine and alcohol) to help them cope with a biological clock that is out of synch with society’s clock. Roenneberg also demonstrated that “living against the clock” may be a contributing factor to the growing epidemic of obesity.

I’ve taken Roenneberg’s Chronotype Questionnaire and determined that I’m an Owl(ish) person. Discovering this was such a great insight because although I’ve always wanted to be like those super-mums I know who rise with the sun to exercise or meditate before their kids get up, I’ve just never been able to make the routine stick. In an ideal world, I’d hit the hay at about midnight and rise at 8:00am or 9:00am. (As I’ve written about previously in my “How Much Sleep Do You Really Need?” post, when I did a simple exercise to determine how many hours of sleep I need each night, I discovered that anything short of nine hours leaves me feeling depleted). Being Owl(ish) means that I find my stride in the late afternoon and early evening. Unfortunately, with an early bird 3-month-old baby and a 3-year-old toddler in my house, the Owl(ish) schedule is not practical. As a result, I’m often challenged to get enough sleep.

But there is good news if you’re like me and don’t have the luxury of manipulating the world to suit your chronotype. While your internal clock does play a role in determining your sleep time preferences, so too does the amount and type of light you’re exposed to during the day. In one fascinating experiment, Kenneth Wright and his colleagues from the University of Colorado took a group of men and women camping in the Rocky Mountains for a week. They slept in tents outdoors and were banned from using artificial light sources such as torches and cellular phones. In just one week, their internal clocks shifted. “All chronotypes had moved very close to each other. The late types had moved furthest towards the early types, but even the very early types have moved a bit later,” said Roenneberg, explaining that by being more strategic about light exposure, we can tweak our internal clock.

As I wrote in my blog post “Is Artificial Light Wrecking Your Sleep?”, in our house we now have almost no blue light after sundown. We purchased inexpensive orange and red tinted globes from our local hardware store for our lamps. This has been particularly useful at the moment as I’m nursing my young son who gets hungry during the night. By not using any blue light, we’re both staying in a kind of sleepy-haze during these night feeds and falling asleep easily when were done. We also found a red light to put in the electrical sockets in our bathroom, so that we don’t need to turn on the bright overhead light to use the bathroom at night. On the occasions when I watch television, I aim to switch it off an hour before I intend to sleep, but generally, I use my evening hours to practice yoga, do my household chores while I listen to an entertaining audio book or podcast, read, or take a relaxing bath. If I’m working on my computer in the evening, I wear rather daggy-looking orange tinted glasses that filter out blue light. 

The results of these small changes have been dramatic. I feel sleepy much earlier than I used to and fall asleep much more quickly. I find it remarkable that these simple steps can make such a big difference.