Into the night…

Emergency and critical care is a 24/7 job, and requires us to pull some pretty crazy shifts. It is well documented that shift work has a number of detrimental effects on our health, both mental and physical, so it pays to be properly informed.

One of my big areas of interest outside of veterinary medicine is sleep hygiene and medicine. I’ve always been a light sleeper and used to (pre-internship…) struggle falling asleep. This has meant I’ve looked into the various ways we can manipulate our body to help get that much-needed shut-eye.

I’m predominantly going to be nocturnal throughout the month of April due to how my shift patterns have fallen with three lots of Saturday to Tuesday nights, so I figured now would be a good time to discuss some of my practical tips for those of you working nights.

For reference, one of my go-to articles for explaining the issues facing shift workers is by Potter and Wood (2020) – I’d really recommend you check it out as it’ll provide some key info that I’ll try to break down here.

Getting that caffeine buzz

I love coffee, and coffee loves me – or does it? I don’t really get much of a “kick” out of drinking coffee anymore – probably because I’ve become so desensitised to the effects of caffeine from years of constant abuse.

Caffeine is essentially a recreational drug – it’s addictive, you build a tolerance and it has long-lasting effects on your body. Caffeine works by blocking the adenosine receptors in your body. Think of adenosine as your “sleep hormone”. As you go through the day, adenosine is produced as a by-product of metabolism, and its levels are correlated with how “sleepy” you feel.

Well, caffeine tries to interrupt that. Caffeine blocks the action of adenosine on the body by interfering with the adenosine receptor – but here lies an important point. Caffeine doesn’t get rid of adenosine, it merely blocks its action. This explains why often people will crash after a dose of caffeine; your adenosine continues to build up and bam, the caffeine wears off and you get a sudden increase in adenosine binding.

But the really interesting fact about caffeine is its half-life…it’s pretty long, but quite variable. Studies have shown that the half-life of caffeine ranges anywhere from 2-12 hours (Cappelletti et al, 2015), and we each metabolise caffeine at different rates.

For some, caffeine may have a very minimal impact on sleep, and you can go ahead and slam that double espresso before bed. For most, though, it makes sense to try to limit your caffeine intake in the hours before bed.

The aforementioned article by Potter and Wood (2020) recommends that you should try to stop caffeine intake a minimum of seven hours before your biggest sleep period. Your results may very well vary – we know individual metabolism can dramatically differ from person to person – but if you’re struggling to get to sleep this is probably a good place to start.

Light and the circadian rhythm

I’m not going to go into the depths of our circadian rhythm physiology because a) it’s not my area of expertise and plenty of resources are out there, and b) it’d probably be a great way of getting you to fall asleep before the end of the article.

The basics are that we have an endogenous biological clock that roughly spans 24 hours a day. Peaks and troughs of various hormones, such as melatonin, help regulate our circadian rhythm to ensure we get proper sleep. Now, before the advent of the lightbulb, this circadian rhythm was very much in tune with the environmental light-dark cycles – dark outside = sleep, light outside = awake.

Unfortunately, our bodies are no longer subject to this natural environmental rhythm. We try to emulate this in the hospital by altering the light level in the ICU, but it’s still pretty bright. We’re so dependent on screens nowadays – whether that be your phone, computer, tablet – it’s so easy to get that light into our retinas.

So, what can we do about it? Well, there’s a bit of a two-pronged approach here. We know light early in our waking day helps to calibrate our circadian rhythm. Obviously, during daylight hours this light comes from the sun. Getting out and about in the sunshine is a fantastic way to help you calibrate your circadian rhythm. But what about those of us working the night?

Well, you may have heard about seasonal affective disorder (SAD) lights. These lights emit large amounts of “lux” (the measurement unit for light) with the idea that they replicate some of that sunlight. These SAD lights come in various sources – most commonly a box that you have to place close to you. Not the most practical, but they can definitely be placed nearby while you eat your breakfast.

Other, more fancy options include wearable tech that shines light directly into your eye at levels that don’t cause discomfort, but help to synchronise your circadian rhythm (more on this in the article by Potter and Wood [2020]). As I said, this isn’t my area of expertise, but anecdotally I’ve found benefit from starting my “day” with a dose of light, whether that be from a light box or the sunlight.

At the other end of the spectrum is our light exposure at night. Trying to reduce the amount of light exposure we get is a great way of helping you feel sleepy. This can be achieved in a number of ways, and the most recent smartphones and laptops often have built-in apps to help you regulate this.

For example, f.lux is a macOS app that gradually reduces the amount of blue light being emitted from your screen. Likewise, the “night shift” feature found on iPhones can do similar. It takes a little getting used to, but I don’t really notice the darker shades anymore.

If you want to take it a step further then blue light blocking glasses have some scarce evidence behind their use, but for the majority of “good” ones, you’ll have to commit to having orange-tinted lenses – not the most stylish, unless you’re a competitive cyclist.

Melatonin supplementation

As already discussed, melatonin is a hormone that is heavily involved in your circadian rhythm and helps to produce the feeling of tiredness by simulating “darkness”. Our pineal glands (think back to synchronised breeding of sheep…) produce melatonin when it gets darker and it helps us fall asleep, as well as having many other effects on the body.

In the absence of a normal environmental clock, however, our melatonin production may not synchronise with our sleep cycle. Supplementing melatonin in the hours before bed can help you fall asleep faster. It won’t keep you asleep, but it’ll help you fall asleep.

We all respond differently to different doses of melatonin, and I am not in a position to make any nutritional or dietary recommendations to anyone, so have a read and make your own informed choice. Again, the article cited previously by Potter and Wood (2020) has some basic recommendations and links to further research on the topic.

Last but not least, sleep hygiene

One of my favourite books on sleep, Sleep: The Myth of 8 Hours, the Power of Naps… and the New Plan to Recharge Your Body and Mind by Nick Littlehales, puts it very bluntly: “The bedroom is for sleep and sex only.” In our modern day, the bedroom has become much more – it is a place of safety and relaxation, but often that comes with additional hazards that we should probably be aware of.

Everyone has differing opinions on this, but many people will eat food and watch TV in bed – now, if you do this regularly, why would your body be conditioned to fall asleep in bed? One of the simplest things you can do to help your sleep is to create the best sleep environment.

It varies from person to person, but general recommendations are to have as close to pitch-black darkness as possible (remove any additional light sources such as the red lights that shine on TVs to make you aware they’re not actually on…), a cool environment (when we used to sleep outside, it undoubtedly got cold) and a quiet environment with some background noise (not after complete silence here).

Many, many ways to manipulate your sleep environment exist, but think about it this way: how have we evolved to sleep? We evolved to sleep when it was dark, when it was cold and when it was quieter.

I’m not saying you need to go all out and get ear plugs and a sleep mask, but for some, this may be necessary. The blinds in my internship room were terrible for keeping light out, so I would always wear a sleep mask on my night shifts. Luckily, now that I’ve moved I’ve got some thick blackout blinds that act to keep not only light, but also heat, out of my room.

Having a routine before bed can really help get your body ready for sleep. Do something that relaxes you: read a book, do some breathing or meditation exercises, or even consider watching some TV downstairs. But Dave, you just said to avoid light exposure. Well, yes, in an ideal world, we wouldn’t be watching TV right before bed – but we’ve been conditioned to find this relaxing, so take some precautions and maybe regulate what you’re watching. But it’s not the end of the world.

What sounds like a more relaxing environment? Going and brushing your teeth before bed in a dim environment with warm lights, or doing the same in hospital-esque brightness – I’m sure you’ll agree, the former is probably going to be less stimulating.

That’s all folks!

Sleep science is a fascinating, evolving and diverse area of research. As I said previously, this is not my area of expertise, but I’ve done a lot of reading around the area over the past few years.

The article referenced previously by Potter and Wood (2020) is a fantastic review on the topic and I’d highly recommend it to anyone who works shift patterns.

Shift work has long-term effects on our bodies, and the best way to minimise these detrimental effects is to be proactive and recognise areas where you can improve. I never sleep for as long during the day when I’m working nights, but the discussed strategies have helped me improve the duration and quality of my sleep over time.

If you have a question or want to discuss an ECC Endeavours topic, feel free to drop me an email at [email protected] and I will try to get back to you ASAP. Until next time, take care.