I often find napping ‘advice’ not so straightforward. News articles tries to give you tips from authors who have little interest in sleep, and often just pick up on the ‘latest’ study and apply it to the general population.
To nap or not to nap is often the question. Limiting it to these binary conditions means we often ignore all the grey areas in-between; like when to nap? How to nap? What to do if you are unsuccessfully trying to nap?
Many scientific papers have already concluded that napping is good for you. The few reasons not to nap is generally based on if you have insomnia or medical reasons not to nap. If you live your life on a regular daytime schedule and you are napping 1 or more hours a day, then you need to understand why you need to nap so much so regularly. There may be an underlying health problem or issues with your nighttime sleep. If you are a night shift worker, you are already subjected to sleep deprivation and need to understand how napping supplements this sleep deprivation.
Circadian disruption and your environment are two factors that play a role in night shift sleep deprivation. Let’s look at what roles they play.
Circadian disruption is one of the many challenges that come with shift work. Your circadian rhythm regulates many key processes in your body such as your sleep wake cycle. Your circadian rhythm makes sure your body’s processes are optimised at various points across a 24hr day and are connected to your internal clock in the suprachiasmatic nucleus (SCN).
Humans are strongly governed by the sun, with light being one of the strongest timekeepers (zeitgeber) that our internal body clock uses to stay on track with the 24hr day. Jürgen Aschoff found in his bunker experiments that when our internal body clocks are left to ‘run freely’ they struggle to keep to 24hrs. Exposure to light at certain times of day will either lengthen or shorten your internal day to keep it in sync with the Earth’s rotation.
Within the 24hr cycle, we all have different times when our body processes are optimal such as our sleep-wake cycle or digestive system. In our sleep-wake cycle, some people get the onset of sleep earlier and prefer to wake up earlier, while others are late types and prefer to sleep later and wake up later. We also see a difference in how much sleep people need; some of us it's around 7 hours and others can be 9 hours. The great thing with averages is that few people fit into the average, so it is often useful to look at sleep need and timing as a range with 8 hours being the average.
When working night shifts, our internal clock never fully adjusts to it; that’s why many of us struggle the most during a shift in the few hours after we would have normally gone to bed. The exposure to light and the challenges to keep a regular eating schedule for many nightshift workers makes it harder to adjust. The result is sleep deprivation; when you finally get a chance to sleep your body doesn’t want to sleep and your circadian rhythms are all over the place. Even though you are exhausted, you tend to not get the full amount of sleep you would need and the quality of sleep you have is more disrupted. It's like living in constant jetlag.
Over 20 years of research has shown the impact circadian disruption has on the health of nightshift workers, to an extent that the world health organisation now classifies circadian disruption as a potential carcinogen.
The environment around us plays a big part in being able to switch off and fall asleep. If you sleep during the day, you can be affected by the light around you, as mentioned before light plays a big part in the circadian disruption. The noise from the street, cars and housemates can impact the quality of sleep we have even if we are able to nod off.
In addition to this, you tend to be more physiologically aroused as people are out and about doing things and the world around you is awake. These factors can shorten your sleep time; it is the sociable hours where we want to meet our friends, do our shopping, and go to the bank. Many night shift workers feel some level of pressure to do things during the day when they should actually be sleeping.
How does shift work disrupt – and how can napping help counteract them?
I am only going to talk about the short-term impact of shift work sleep disruption and how it affects your day. There is lots of research on the long-term implications of sleep disruption from night shifts but that’s for another article.
Sleep deprivation can affect your appetite and cravings, cognitive ability and alertness, your mood, and insomnia (your ability to get to sleep and stay asleep at night).
These are just some of the impacts of sleep deprivation. When you are sleep deprived even for a couple of hours your body craves foods rich in carbohydrates and sugar, your hormones (ghrelin and leptin) are disrupted so you tend to get hungry more and eat more food when sleep deprived and on top of this, your self-control is also reduced.
This doesn’t just impact your decision-making with food but all of your general decision-making. A lack of sleep depletes your self-control; the less you sleep, the worse you become at filtering the prejudices you know are wrong.
Napping can improve the time it takes to make a decision and the quality of the decision. Research led by the University of Bristol looked at whether a short period of sleep can help us process unconscious information and how this might affect behavior and reaction time. The findings reveal the benefits of a short bout of sleep on cognitive brain function and found that even during short bouts of sleep we process information that we are not consciously aware of.
A few hours of sleep deprivation can also impact your mood; you tend to adopt a more negative bias towards events around you, which can result in higher emotive responses to stressful situations. When you are sleeping your body reduces your cortisol levels and helps your brain process what you have been through the previous day. People suffering from sleep deprivation will tend to have higher levels of cortisol (the hormone associated with fight or flight) and their reactions to events around them will tend to be more erratic.
A study at the University of Michigan by Jennifer Goldschmied found that after waking from a 60-minute midday nap, people were less impulsive and had a greater tolerance for frustration than people who watched an hour-long nature documentary instead.
One of the most commonly touted reasons for not having a nap is sleep inertia; the groggy feeling you have when you wake up. I feel the message is delivered wrong, we shouldn’t avoid napping because of sleep inertia, we should manage sleep inertia. Generally, the groggy feeling will last for 15 minutes after you wake up and you will not get it after every nap. You can anticipate this by taking a walk, getting fresh air, or not diving into mentally straining work as soon as you come out of your nap. This can make the inertia period more pleasant. Overall the improvements you get from the nap far outweigh a groggy feeling when you wake up.
An analysis of 13 mixed-method studies found that ‘despite short periods of sleep inertia immediately following naps; night shift napping can lead to decreased sleepiness and improved sleep-related performance.
As you can see, there is a significant impact on your day from sleep deprivation, and getting a nap to compensate for this can be very valuable. I often hear that a health care workers operating at 50% is still equivalent to ‘the average person’ operating at 100%, it makes me smile because I can appreciate how hard they work but you deserve the opportunity to function at 100%. Don’t limit yourself or your team by failing to get enough rest.
Check out our next piece on how to nap during a night shift. We will look at what times, how long, and where. We will also look at ways you can improve your sleep when you are working night shifts.
How to transform UK healthcare environments to support doctors and medical students to care for patients - Professor Michael West and Dame Denise Coia on behalf of General Medical Council