Our body’s basic rhythms, in particular our sleep and wake cycles, rely on light exposure. Production of the all important sleep-inducing hormone, melatonin, is key in our preparation for sleep. However, melatonin suppression caused by light is at the heart of much of the research linking nighttime light to sleep disorders and even poor health.
The good news is, we don’t have to revert to pitch black evenings without light; we just need to understand and use the correct type of light according to the time of day.
First, let's look at a little bit of light science - Lighting is based on colour temperature, which is measured in kelvins. Imagine a scale from 1000K (very red - like firelight) to 10,000K (very blue - light the sky during the day) (actual scale is wider). The higher up the scale you go, the closer the light resembles blue daylight. Blue light regulates our secretion of melatonin. When exposed to blue light, we limit our production of melatonin, causing us to stay alert and awake; in the absence of blue light, melatonin production ramps up, and we get sleepy.
This system worked quite well for a long time. Reddish light from fire (our formerly primary source of nighttime illumination) has little to no effect on melatonin production, so sleep wasn’t disrupted when we relied on fire. These days, though, we’re subject to a steady barrage of blue light - at night, we tend to sit in front of blue light-emanating appliances, and our sleep suffers for it. Television, computer screens and tablets, even digital clocks with blue numbers – they’re all common sources of late night blue light that can affect our production of melatonin.
The effect of even a brief amount of light is long-lasting. Bright light late in the evening — around midnight — can push your sleep/wake cycle back by half an hour or so, making you sleepy later in the evening the following night.
Here are some top tips to unwind and get yourself ready for a good night’s sleep
- Get up and out - blue light exposure during the day is essential to regulate our sleep hormones and increase our energy. Try and get your daily dose of natural light every day.
- Prepare your body for winding down in the evening. Close your blinds and curtains and switch off your main light sources.
- Choose peripheral, low lighting for a cosy, relaxing atmosphere that allows your body to prepare for sleep - ideally choose warm white as opposed to cold white bulbs (3000k and below) as these do not inhibit melatonin production
- Try to avoid blue light sources for at least 2 hours before bed - the main culprits are tablets, screens and smartphones.
- Keep the lighting low in your bathroom too as the bright light just before bed can wake you up. Battery operated candles are a good trick here.
- Avoid taking your phone to bed and opt for a good book or good company instead :)
Wishing you all restful evenings and sweet dreams. xx