Sleep Science

Timing sleep to your natural rhythms is key to a restful night

05 Jan 20238 min read
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Our brains run at a thousand miles an hour during a typical day, with attention bouncing between multiple thoughts each minute. Having minds and emotions working at such a pace can compromise our ability to calm down at night — something we need to do in order to sleep well. This is the view of Chloe Angus from Cavendish Cancer Care, an independent Sheffield-based charity caring for people living with cancer. 

Sleep issues and fatigue are key problems experienced by those supported through Cavendish, making their therapy team experts in sleep health and sleep stress. Difficulty sleeping is an issue that can affect us all, and is particularly common among those affected by cancer. 

The sleep window

A popular concept the centre uses when exploring sleep health issues with patients is that of the ‘sleep window’. This describes the most optimal time period within which an individual should fall asleep. It is a period when the brain wants and expects sleep. Going to sleep during this time allows us to enjoy the best quality of sleep. 

A useful analogy to describe the sleep window involves picturing yourself at a train station late at night, waiting for a connection. When the train finally arrives, you can either board it and head to your destination or miss it and wait for the next train. 

Everybody’s sleep window will be different; the time period associated with your sleep window will come down to you as an individual.  

Chloe says: “If you are able to fall asleep in your sleep window, you are much more likely to have good sleep, but there are other impacting factors such as stress and alcohol which will counter this.”

Thinking about your sleep window can help when looking for a routine that prepares you for sleep. This routine may include the best time to eat and how to most effectively wind down at night. 

Chloe adds: “If you develop a good sleep routine and regularly fall asleep in your optimal window, you create a good brain habit for sleep which has a positive impact on your overall sleep status.”

But how do we find our sleep window?

All our bodies experience natural circadian rhythms. These are internal cycles that occur over a 24-hour period. The peaks and troughs associated with these rhythms can cause physical, mental and behavioural changes. At their height, you might, for example,  feel energised for an hour before a dip leaves you in a lull. 

Diet, mood and use of electronic devices can all alter our alertness and energy levels. Chloe suggests that being aware of these factors should help you find it easier to tune into your body and recognise when you feel the most tired. And remember, recognising your sleep window is individual to each person, so there is no “correct answer”. 

“We encourage curiosity and openness to raise awareness of when you naturally start to feel sleepy,” she says.

“We suggest a good idea is to begin experimenting between 9:30pm and 11:30pm, most people’s optimal sleep window falls within this time.”

Obviously, our regular morning obligations are going to have the greatest effect on when we need to fall asleep. Work, exercise, school run — our daily start time is the primary factor that determines our nightly bedtime. 

Ideally, we want to aim for 8 hours of sleep. It would be great if it were as easy as simply working back 8 hours from the morning start point, adding extra time if we found we still felt groggy and tired. However, there are often a number of other factors that can affect how we wake up, from what we have drank or eaten the day before to any worries or stress we have at that moment.

Much of how we feel when we wake up and whether we hit the snooze button is related to our plans for the upcoming day, not just our sleep that night.

Tips for finding your sleep window

The following 8 tips are some practical suggestions for identifying your sleep window:

  1. Use the standard 8 hours of sleep a night as a benchmark. For example, if you need to get up at 6am, you ideally want to be asleep at 10pm. But be prepared to make adjustments to this.
  2. We know from the rhythms of our body that, for many, it is not simply the case that we go to bed at 10pm and fall asleep straight away. Consider preparing yourself for sleep with routines and habits during the evening and day that help you avoid anything which can impact your sleepiness. 
  3. Limit your caffeine intake. Ideally, drink nothing that contains caffeine after midday.
  4. Cut out late-night snacking — eating food close to bedtime can keep us awake. Finish eating any food at least 2 to 3 hours before you want to fall asleep.
  5. Resist looking at electronic devices late at night. The blue light you receive from phones and other electronic devices is known to overstimulate the mind. Although we know blue light is bad for sleep, it’s often the type of content you are consuming that is worse. Engaging films and binge-worthy TV can make you too alert to sleep. Notifications also work to pull our attention away from sleep. Switching off notification alerts and using nighttime filters will help to minimise these effects. Aim to switch off from this at least 1 hour before bed.  In fact, keeping electronic devices out of the bedroom altogether can be the best option for some people.
  6. Develop a nighttime routine that relaxes you. This could include reading, listening to relaxing music or even performing a soothing skincare routine.
  7. If you’re struggling to switch off the thoughts going around your mind, try relaxation techniques. These can include meditation or simply writing your thoughts down in a notebook. Making a to-do list for the next day can help soothe your mind and improve your sleepiness and sleep quality.
  8. Create a rough sleep diary that outlines your daily ‘deadlines’. Something like:
    • Last caffeinated drink at 12 noon – herbal or decaf in the afternoon.
    • Evening meal to finish at 7pm.
    • Switch off from TV/phone and start evening relaxation routine at 9pm.

With these distractions out of the way, you will more easily discern when your body usually wants to fall asleep.

Now I have my sleep window, how to stick to it

Certain messages common within modern society can cause us to view sleep as a luxury rather than a necessity, making it easy to miss our desired sleep window.

Clare Longstaffe, a hypnotherapist at Cavendish, has expertise in stress, anxiety, pain, phobias and fears. 

She asks us to consider the modern “hustle culture” promoted by some celebrities, where stars pride themselves on only needing a few hours of rest at night. When these sorts of choices are linked to success in achieving life goals, the message can become harmful.

Another tendency that can also have an effect is today’s “scarcity culture”. This describes the repetitive feeling of “not having done enough”, and is often accompanied by the urge to not stop until everything is done. This can lead people to compromise their time for rest and recovery. 

Clare says: “The most important element of good sleep is understanding what works for you without stressing.” 

We currently live in what many people have coined the “attention economy”, where our attention is grabbed from many different directions at once. These distractions make it difficult for us to rest and relax.

‘Revenge Bedtime Procrastination’ is another psychological pitfall that can disrupt sleeping patterns. Well known among Far Eastern cultures, this describes when someone chooses to stay awake because they feel like there isn’t enough time in the day. They are effectively sacrificing hours of sleep for extra free time. The tendency often occurs in people with demanding schedules who feel they don’t have enough control over their lives during the day; by refusing to go to sleep early, they gain control and personal time. 

Clare adds: “The child within us wants to keep us awake and make the most of the day, which can cause us to feel wired even as we prepare to sleep.” 

It’s helpful to consider that busy, tired minds can lead to overthinking at night. Our limbic system — the area of the brain related to behaviour and emotion — is more prominent at the end of the day, which causes us to be more emotional. This makes it easier for thoughts to escalate at night time. 

By taking a little time and consideration in the lead up to bedtime, and avoiding some of the modern pitfalls of busy modern living, we can better understand our body’s daily requirements and what our body is trying to tell us. This will bring us closer to our natural sleep patterns and, ultimately, a more soothing and restorative night’s sleep.

Chloe finishes by saying: “A helpful concept we use at Cavendish is the idea of an accelerator and a brake; most of us are on the accelerator all day but this means it is harder for us to slow down at night. If we keep applying brakes throughout the day this really supports positive rest.”