Struggling to sleep? Your circadian rhythm could be to blame

A woman sits up and rubs her neck in bed as a man sleeps soundly next to her

If you suffer from the dreaded 3pm slump, listen up

17 September 2019 4 minute read

Do you suffer from the dreaded 3pm slump? You can blame your circadian rhythm on that!

What is your circadian rhythm?

The circadian rhythm is your body’s internal clock that regulates when you feel sleepy or wide-awake.

The circadian rhythm governs more than just sleeping and wakefulness, however. Over the course of a 24-hour day, your energy levels will naturally peak and drop at different times, as your circadian rhythm is responsible for hormone production and release, and other biological processes like cell production and body temperature.

The circadian rhythm is heavily influenced by two things: exposure to light and mealtimes. Anything that affects those two things, like international travel and shift work will have a major effect on your wellbeing.

Interruptions to your circadian rhythms

Jet lag: One of the toughest things you can do to your circadian rhythm is to fly across time zones, so that the time you would usually call night becomes a bright and sunny day, and vice versa. If you’ve ever had jet lag, you’ll know that it can take about a week for your circadian rhythm to adjust to the new time zone.

Shift work: Harder still is adjusting your circadian rhythm to working a night shift. Without the light cues to support waking and sleeping, your system has to work extra hard to adjust. So hard, in fact, that in 2007 the World Health Organisation listed shift work as a carcinogen, as it is linked to higher rates of cardiovascular disease and cancer. If you’re working nights, check out our article for tips on how to stay healthy as a shift worker.

Credit: nib health insurance

Circadian rhythm and the impact on sleep

Although our circadian rhythms vary slightly from person to person (night owls have more energy in the evening, for example) we generally experience our biggest energy dips between two and four in the morning and between one and three in the afternoon. You’ll notice these dips more if you’re already sleep-deprived.

Light has one of the biggest impacts on the circadian rhythm. We’re wired to rise with the sun and settle as it begins to get dark. ‘Blue light’ which is the light found in sunlight as well as LED, fluorescent lights and screens (TVs, computers and phones) suppress the secretion of melatonin, the hormone needed for sleep. This is why working on a computer, watching TV or scrolling through your phone before bed will make it harder to drift off to sleep.

Your circadian rhythm has an enormous influence on not only your health but also your physical and emotional wellbeing and the good news is that it is within your power to change it. Respecting its natural cycle (rather than cheating it with caffeine and relaxants) will help you feel better and think more clearly.

An infographic displaying the four stages of sleep - light sleep, onset of sleep, deep sleep, and REM sleep, and their benefits

How to change your circadian rhythm

Embrace routine

Your circadian rhythm loves routine, so begin getting up and going to bed around the same time each day. It’s ok to change your routine on weekends, however try not to deviate from your weekday schedule by more than an hour.
Give yourself a screen curfew

To avoid melatonin-disrupting blue light, try switching off your screens at least half an hour before you want to head to bed and curling up with a good old-fashioned book instead. Most smartphones, computers and kindles allow you to program a time at which they switch to night mode and filter out blue light.
Keep naps short

Any longer than 30 minutes and you may find it harder to sleep at night.
Avoid the snooze button

I know! We all do it. ‘Ten more minutes… zzz’, but hitting snooze will not only reset your internal clock, it will give you an incomplete sleep cycle and so the sleep you do get will not be restorative. Try shifting the alarm clock away from your bed so you have to get up to turn it off.
Exercise early

Exercise boosts your adrenalin for several hours. Great for the morning, but a late-night jog could make it harder to sleep.
Get natural light as early in the day as you can

Natural light is great for resetting your body clock, which is why people who travel to different time zones are advised to get early morning sunlight.
Create a bedtime routine

Whether it’s an evening bath, journaling or reading a chapter of your book, a consistent night-time routine helps your body recognise that it’s bedtime.
Eat with the sun

By giving yourself a ‘food curfew’ of two to three hours before bed, you'll give your digestive system a rest and find it easier to sleep more deeply as a result.
Use caffeine early

While we all respond to caffeine differently, it typically takes four to six hours for caffeine to leave your system (and more if you’re caffeine sensitive).
Schedule your activities

Schedule tough mental tasks for earlier in the day as most of us have an energy peak mid-morning, then try to focus on simple administrative tasks like emails in the afternoon slump.
Practise mindfulness

Practising mindfulness is also shown to help you get to those sweet dreams quicker. For more, check out our beginner’s guide to mindfulness.