By Sean Gay
You look up at the clock, then at your calculus teacher. After listening for what feels like hours, you look back at the clock. It has only been one minute. You feel your eyes get heavy and you slouch in your chair, only to be awakened by your teacher asking you to answer a question. As you try to tell her that “I was asleep and if I don’t sleep I’ll DIE” The teacher laughs and says “Fair enough, but get that sleep at night not during my class”. As a sleep scientist I often wonder why we feel the need to take a nap, especially during the middle of the day? Is napping even good for you? If so, how should you nap?
Why do we feel the urge to nap?
To answer this question, I have to first explain why we need to sleep. The need to sleep consists of two facets: circadian rhythm (or your body’s day to day routine) and homeostatic sleep drive (the longer you are awake the more you need to sleep). Circadian rhythm is primarily controlled by sunlight, which is why you feel tired after dark and more alert when the sun is up. Homeostatic sleep drive which is a fancy way of saying the longer you are awake the more you want to sleep. Contrary to popular belief, feeling tired the longer you are awake is caused by your brain not your body, which is why playing video games can be tiring. Why is this the case? It is because your brain is made up of cells called neurons, which fire electrical pulses to communicate with other neurons and cells in the brain. These neuronal connections strengthen while you are awake, to help you retain what you do throughout the day and learn. At the end of the day the number of neuronal connections are maxed out, which puts strain on the brain. Sleep contrasts this and weakens many connections, with select few connections continuing to strengthen. As such, sleep restores your ability to learn and make memories by returning your neuronal connections to a more reduced level. You can liken this process to your room getting messy during the day and then at night it is cleaned up and organized, allowing you to use your room the next day. Not having enough sleep, i.e. after studying all night for an exam, prevents you from ‘cleaning your room’ and having a well functioning brain, which makes you crave sleep. In summary, homeostatic sleep drive is why you feel the urge to take a nap, even at noon during class.
Are naps beneficial? If so, how?
It depends on the definition of a nap. 10 -20 minute naps have been shown to be beneficial, whereas longer naps usually are not (read section below). Within this short time frame, you are able to hit the first cycle of sleep without reaching the other deeper cycles of sleep (see image). The deeper stages of sleep, particularly stages 3-4, cause sleep inertia, or a period of drowsiness following sleep. When you wake up during these deeper stages your brain can not quickly adjust to being awake and needs time to do so, hence feeling groggy. By avoiding sleep inertia you can wake up feeling refreshed instead of groggy. Naps are beneficial because even the first stage of non-REM sleep allows your body to cool down, physically relax, and slow down brain activity. This short nap can reduce fatigue, increase alertness and improve mood for the rest of the day. There is even evidence that napping can help with retaining memories, such as the facts you try to learn during a long study session. Outside the USA there are many cultures that regularly take mid day naps. Such countries include Spain,where they take siestas, a 2-hour midday break, or Japan where they take inemuris, working yourself so hard you fall asleep at your desk, which is a badge of honor for them. In countries where midday napping is normal, productivity tends to be higher ,particularly late afternoon, because naps help people avoid the midday slump that is normal in most people. All in all, naps have many benefits, can be a great way to make up for lost sleep at night, and can even become part of your daily routine.
What are the drawbacks of naps?
The largest drawback of naps is their potential to disrupt your sleep at night. Your circadian rhythm makes you feel groggy at night and homeostatic sleep need peaks at night before bed. This allows you to stay asleep throughout the night and have your highest quality of sleep, which is important because no nap can replace sleep. Napping too close to bed time or for too long can offset this sleep balance by diminishing your homeostatic sleep need, not allowing you to feel as sleepy as you should at night. If you suffer from insomnia napping can especially be disruptive.
How should I nap?
In order to have the most beneficial naps you must consider when you sleep and for how long. Here’s some advice to get the most out of your nap:
- Set an alarm clock
As mentioned above, a high quality nap should not be too long. If you sleep too long you will not reap the benefits of napping but rather feel groggy and inattentive afterwards.
- Do not nap too late in the afternoon
It is recommended to not nap 6-7 hours before your bedtime. The most optimal time (if applicable) is after lunch, when you begin to hit the natural midday slump in your circadian rhythm.
- Create a sleep friendly environment
To make the most of this short nap you must feel relaxed to reap the benefits. This could be as simple as taking some breaths before napping or wearing ear muffs to block out surrounding noises.
In conclusion, napping isn’t just a habit for the lazy, but can really help you overcome a midday slump. Just make sure to consider when and how long you nap before you do. So go ahead, close your eyes and reap the benefits of napping, just maybe not during the middle of class!
