The Impact of Light on Sleep
It’s January. The clocks turned back months ago. The darkest day of the year has passed (which btw, Dec 21 is both my favourite AND least favourite day of the year - I cry for the darkness but it’s only getting lighter from here on in!).
But it’s the new year. It’s cold where I live. And it’s still dark. We have a ways to go until we can bask in those late summer evenings, sipping a drink or having a bite on a patio as the sun descends.
But what does this have to do with your sleep?
Light (and darkness) play a HUGE role in our sleep wake cycle. Our circadian rhythm is what drives our sleep/wake cycle and exposure to light, both natural sunlight and artificial sources (such as TVs, phones and LED lights), can affect and alter when we feel sleepy and alert.
You can think of your circadian rhythm as your body’s master internal clock, ticking away on about a 24 hour basis, so the course of the day. This clock is located in your brain, and it helps influence and regulate a range of different physical, mental and behavioural processes and systems in our bodies, including hormone release, metabolism, body temperature, heart rate, etc.
This internal clock is directly influenced by a range of cues, such as movement, nutrition, temperature and social activity, however, light is THE most powerful influence on our circadian rhythm when it comes to sleep.
When light hits our eyes (ideally in the morning), it sends a message to our brain to wake up and our bodies then release alerting and mood enhancing hormones, such as cortisol and suppress the production of melatonin, which is a sleep hormone. Being exposed to light throughout the day can help keep those energy levels up, regulate our mood and importantly - tell our body that it is daytime.
In the evening hours before bed, when light levels are typically low, the inverse happens. Melatonin gets released, which is a hormone that signals to our bodies to prepare for rest and those morning alerting hormone levels drop. However, if you’re exposed to too much bright light in the evening before bedtime, especially from sources that emit strong blue light signals, the melatonin in our bodies can end up getting suppressed and the release gets delayed. Essentially, our body thinks it’s still daytime with all the bright light cues. Furthermore, serotonin and cortisol, which are supposed to be at a low level at bedtime, get activated by the light and can send alerting signals to our bodies to wake up.
In a nutshell - too much bright light at night can trick our body into thinking it’s daytime, making it harder to fall asleep and not enough bright light during the daytime can trick our body into thinking it’s night time, making us feel sluggish and tired. Our body and our sleep wake cycle loves regularity so if we can get the right amount of light at the right time each day, that helps strengthen our circadian rhythm, which is key for sleep.
Top Light Tips for Sleep:
Immediately upon waking, blast the lights in your home, open up your curtains/blinds and have your breakfast in front of a window if possible
Try and get 15-30 minutes of natural, unfiltered, outdoor light within a couple hours of waking (ASAP if best!) and try and get outdoors for another burst of light around midday
Remove sunglasses when outside for 15-30 min as your lenses block some of that important light spectrum that you want during the day
As the sun goes down in the evening, limit your levels of bright light exposure - use lamps, dimmers or candles in the home
Try and avoid looking at devices that emit blue light (eg. TV, computers, phones, LEDs) 30-60 minutes before bed or consider wearing blue-blocking amber glasses and using blue-light filtering technology on your devices (f.lux, night shift mode)
Sleep challenges can be nuanced. In order to overcome them in the long term, you always want to identify and address the root cause of your sleep difficulties by examining all the potential inter-related factors that may be impacting your sleep.
If you’re suffering from poor sleep, why not connect with a sleep coach? Book a free 20-minute discovery call to find out how I can help.
