Your body has a ‘master clock’ that is located in the cells at the back of your eyes. Whenever light reaches these cells, it sends messages all around your body to help regulate:
- Sleep
- Mood
- Hormones
- Immune system
- Body temperature
- Blood pressure
- And many other bodily functions
It also influences when you feel tired and when you don’t. This is called your circadian rhythm and it repeats approximately every 24 hours. Undamaged, it continues to work in the eyes of people who are completely blind enabling them to follow a natural wake/sleep cycle. The amount of light that you get is crucial to maintaining a normal circadian rhythm.
Sunlight vs other light sources
The type of light you need in order to see is very different to the type of light that regulates your circadian rhythm. The lights that you have in your house, classroom or office can’t compete with the sun. Even when the weather is bad the level of light outdoors is 100 times higher than it is inside.
Disruption to the circadian rhythm due to lack of sunlight and over exposure to artificial light sources, in particular screen-based devices, is associated with poor sleep, depression, anxiety and addiction as well as physical illnesses.
Sleep
Being exposed to more daylight in the morning helps to keep your body clock in sync with the 24hr day which in turn helps you to feel sleepier at night and more awake during the day.
The brighter your daylight exposure, the more melatonin you produce at night. More melatonin will reduce the amount of time it takes you to fall asleep and result in a deeper, less disrupted sleep.
Mood
Sunlight can elevate mood, increase motivation, help with depression and anxiety and stave off Seasonal Affective Disorder (SAD). The availability of sunlight has been shown to have more impact on mood than rainfall, temperature or any other environmental factor.
Vitamin D
Sunlight is the primary source of a nutrient known as vitamin D which promotes bone growth, reduces inflammation, strengthens your immune system and improves cognitive function. Whilst sitting indoors by a sunny window can go some way to helping reset your body clock, it doesn’t help you to produce vitamin D as the ultraviolet B rays needed can’t get through glass.
Lower blood pressure
When you expose your skin to sunlight your body releases nitric oxide into your blood. This helps to lower blood pressure and improve heart health.
Academic performance
Exposure to sunlight can improve motivation and learning and increase cognitive performance and reaction times. A study carried out in 2017 found that students who get more sunlight performed better in assessments.
Tips to get more sunlight
The good news is that a little sunlight goes a long way: often 20-30 minutes is sufficient. Small increases in your exposure can improve your sleep as well as your mental and physical health.
Your exposure time should depend on how sensitive your skin is to sunlight, remember to practise safe sunlight exposure and use sun protection behaviours such as applying sun cream.
Follow these tips to get more sunlight in your routine:
- Set a regular waking time and open your curtains or blinds as soon as you get up
- Aim to exercise outside everyday even if that is just going for a walk
- Try to get outside as much as possible
- If possible, sit close to a window. Even small distances can have a dramatic effect on light levels
- Consider using dimmer lights in the evening if they’re available to you
- Try to not use any screen-based devices for at least an hour before bedtime. This includes phones, iPads, laptops, PCs, Kindles and TVs. Try to reduce your exposure to these devices during the evening
- If you can, use blackout blinds or curtains
- Listen to your body and go to bed when you start feeling sleepy.
