Why do we tend to feel tired when it’s dark outside and more awake and energized when it’s light?
In: 7
There are light sensitive cells inside your eyes that sense blue light to control your circadian rhythm or biological clock. They are different from the light sensitive cells that provide your sense of sight.
Why blue? During the day outside, there’s a large and blue object all around: the sky.
Your biological clock controls the release of the hormone melatonin. Melatonin increases at night and decreases in day. Having more melatonin makes you feel sleepy.
Nowadays with bright blueish white screens on our smartphones and computers, we disrupt our biological clocks and the production of melatonin at night. This can make it harder to fall asleep or have a consistent sleep schedule.
We also sense less blue light in our eyes as we get older. This makes the melatonin production irregular. Older people often end up with irregular sleep.
The lack of blue light exposure can also affect people in the winter when they are cooped up inside. There are methods of light therapy that can help them regulate their internal clock.
Or, the opposite – why am I so tired during the day, but get energized at night after the sun has gone down?
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