The clocks spring forward this weekend and we all know that can mess with our sleep but have you ever wondered why? Matt Walker, neuroscientist and author of ‘Why We Sleep’ has the answer…

What makes us feel sleepy?

Two main factors determine when our body wants to be asleep vs awake. The first is our internal body clock hidden deep within our brain. The clock is responsible for our circadian rhythm – the sleep-wake cycle is part of our everyday pattern and influences many other of our body’s patterns such as mood and when you want to eat and drink. The second factor is chemical substance that builds up in your brain and creates a ‘sleep pressure’ – the more it builds up the sleepier you feel. The balance between these two things influences how awake you feel through the day and how ready for sleep you are at night



What knocks our body clock off balance?

Light levels are our body’s way of resetting our body clock and a clever way to make sure we’re usually sleepier at night and awake in the day. Because the bit of our brain that sets our natural rhythms is sensitive to light they can get confused when we turn the clocks back or forward (and when we skip time-zones – which is why we get jet lagged). Other things influence our body clock too – such as food, exercise and temperature changes. That’s why the patterns we set in terms of how we live our life can impact on the quality of our sleep. Being smart about light exposure (both natural and artificial) and having a routine that signals it’s time to prepare for bed are two smart ways to help your body clock do its thing effectively.


What about sleep pressure?

The other factor that influences when we feel sleepy is the build-up of a chemical in the brain called adenosine. Once levels get to a certain concentration the urge to sleep will be hard to resist, day or night. This usually happens after 12-16 hours of being awake for most people. Walker points out there’s one thing that can ‘artificially mute the sleep signal of adenosine’ and that’s caffeine. Whether it’s in coffee, tea or chocolate – this every day stimulant has a big role to play when it comes to when and how well we sleep. That’s why the advise from sleep pros is to use it during the day but to ease off after dark so you natural rhythms can set the pace.


Find out more about Matt Walker’s book on the the science of sleep here