Tired of telling your kids to switch off?

Well here is some ammunition that might help - or at least give you courage to keep going.

You need sleep to survive. It’s actually more important than food. A gorey detail for the goths … early experiments by a pioneering Russian scientist used puppies who died after just a few days without sleep. More recent studies have shown that the main cause of death for those unlucky test-subjects is rotting food in the intestine. You should have their attention by now!

Not suggesting they’re awake for days on end - and sometimes it feels as though they never get up. But even at an everyday level, poor and irregular sleep has a massive impact their chances of getting through this pandemic - let alone teenage years - as the healthy, happy, successful people they are destined to be. 

A couple more factoids to drop into the conversation as you wait for the kettle to boil… 

• A good nights’ sleep improves declarative memory (ability to remember facts) by 20%
• Disturbed sleep slows reaction time by 20%
• Social jet lag of two hours or more (that’s the difference between sleep / wake times during the week compared to weekends) increases the likelihood of depression by a factor of 30%
• And a Berkeley study in 2018 found that the brain scans of sleep-deprived people as they viewed video clips of strangers walking towards them showed ‘powerful social repulsion activity in the parts of the brain typically activated when humans feel their personal space is being invaded.’ No wonder they're a bit antisocial.

I could go on…

So what can you do about it? You may be relieved to hear that screens are only part of the picture. The lighting makes the world of difference. A recent Scientific Report in Nature by Cain et al (reference in the notes at the end) showed that half of us live in homes that are bright enough to us sleeping properly - although everyone is different. And LED lights are making this worse.

That vital sleep-wake cycle is also known as the circadian rhythm or ‘body clock’. It is triggered by the amount, colour or wavelength and timing of light picked up by a special set of cells in the back of the eye. Other things like food, exercise and social interaction (and a box set of Game of Thrones) help to set this clock too. 

The real problem is that they (and the rest of us) spend too much time during the day in relatively dark, dull places (their bedroom). And too much time at night in the same place (their bedroom). So their body clock doesn’t know if it’s coming or going. And, to make things worse, a teenager's clock is shifting by around two hours - more on that next week.

Just 16 years ago, scientists discovered a special group of ‘day-night’ cells in the human eye. They are tuned to spot a particular blue-ish wavelength of around 470nm (the 'MEL' in this diagram).

There’s lots of that in sunlight in the morning. So, not surprisingly, the brain interprets that wavelength a sign that it’s time to be up and about. Those cells are much more sensitive at night than during the day. So even a small amount of blue light - like an iPad at arms’s length- is enough to get their brain up and out of bed and back online.

That wake-up signal suppresses a hormone called melatonin. It’s known as the sleep hormone because it prepares the body and brain to go into rest and reboot mode. That apparently 'dead' time is, oddly, just as active, as the 'waking' state. 

It takes as little as 10 minutes of bright light, particularly blue wavelengths to disturb that delicate cycle - and around two hours for it to get going again. 

The lighting industry has coined the term melanopic lux or ‘biologically active’ to describe how much a light source will disrupt that melatonin pathway. 

A whole new generation of lighting products are responding to this new understanding of the impact of light on our bodies and brains. Chips that replicate the sun's full spectrum of wavelengths, products that change colour and brightness to reflect the shifts in sunlight at different times of day. 

Very exciting. But it can all get a bit geeky with new standards and numbers coming out all the time.

But in simple terms there are three things to think about when looking at how to give their unhappy body clocks a helping hand - and help you feel a whole lot better too.

• 'Colour'. Sometimes called 'daylight', 'cool' or ’blue-ish’ (like the midday sun or the glow from a computer screen) - is a wake-up call for the brain. On the box, you're looking for a higher number - 4,000k or above. Warm, mellow, yellow-ish (think sunsets, candles and campfires) is a chill-out signal for the brain. Those will have lower numbers - 3,000k and below.
• Brightness. Basically bright = day, dim = evening, dark=night. It used to be simple with 'watts' (the amount of electricity flowing through the filament). LEDs are a bit more complicated - and what really counts is the amount of light getting to your eye (so a bright light on the other side of the room will be very different to the same light sitting on your desk). Experiment with a free light meter to see what light levels you have in different parts of your house and different times of day. As a guide aim for 300-500lux is for daytime working.
• Position of the light - light from above and reflected from walls and windows is more ‘biologically active’ than light on a horizontal surface - makes sense when you think of our history outside.

So in practical terms…

Make their days bright and busy - for their brain at least.

Get out of that cave - draw the curtains and get outside in the morning before 10. Outside is best. Not only is it brighter out there, there are more interesting things for their brain to process than the zoom call or the four walls of their room, however many posters and fairy lights there are in there.

Activity and social interaction is another way their brain clocks it’s daytime. They can take the phone along too - their eyes will be getting the wavelengths they need while they catch up with their friends

• Give them as much bright light as you can during the day to keep that body clock alert. Move the furniture so they have a clear view of the great outdoors. Even if it’s miserable out there, the light levels will help to set that clock.

Put a bright, daylight lightbulb in the overhead light where they work and use bright lightbulbs in a task lamp to help them to concentrate on the job in hand. There are some cool new task lights on the market and tuneable lights are brilliant. But an old fashioned angle poise is just fine too. It’s the brightness and colour of the light that counts.

Make the evenings calm and relaxing

• Two hours before bed - log off personal screens and devices - oddly enough, a TV isn’t as disruptive as a screen because it’s further away from your eyes - just try to avoid the thrillers!
• Switch off the bright overhead lights
• Switch on low-level lamps fitted with warm yellow-ish lights - 40 lux is plenty to listen to a podcast, to revise written notes - or, heaven forbid - have a conversation!

Making that watershed and sticking to it is a great way for them (and for you) learn about time management too

Embrace the dark

At bed-time - ideally the same every night including weekends, draw the curtains and take all screens and devices out of your bedroom so you’re not tempted to steal a peek at your LinkedIn feed.

Radical thought - consider putting all your devices with the kids’ to charge in the kitchen.

After all if you don’t switch off, why should they?

I’ve been working with the teams at Fagerhult, Seoul Semiconductor and Signify and an international network of scientists. We’ve put together a series of short videos about light and health for the tik-tok generation. Here is our take on the body clock - enjoy!

Some references (might help you nod off!)

About sleep...

Poor sleep triggers viral loneliness and social rejection: Lack of sleep generates social anxiety that infects those around us https://www.sciencedaily.com/releases/2018/08/180815171117.htm

Bentivoglio M, Grassi-Zucconi G. The pioneering experimental studies on sleep deprivation. Sleep. 1997 Jul;20(7):570-6. doi: 10.1093/sleep/20.7.570. PMID: 9322273.

Born J, Wilhelm I. System consolidation of memory during sleep. Psychol Res. 2012 Mar;76(2):192-203. doi: 10.1007/s00426-011-0335-6. Epub 2011 May 4. PMID: 21541757; PMCID: PMC3278619.

National Institute of Neurologic Disorders and Stroke. (2019, August 13). Brain Basics: Understanding Sleep. Retrieved November 11, 2020, fromhttps://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/understanding-Sleep

Ma Y, Liang L, Zheng F, Shi L, Zhong B, Xie W. Association Between Sleep Duration and Cognitive Decline. JAMA Netw Open. 2020;3(9):e2013573. Retrieved fromhttps://doi.org/10.1001/jamanetworkopen.2020.13573

National Institutes of Health. (April 2013). Sleep On It: How Snoozing Strengthens Memories [Press release]. Retrieved November 11, 2020, fromhttps://newsinhealth.nih.gov/2013/04/sleep-it

Peiffer, A., Brichet, M., De Tiège, X. et al. The power of children’s sleep - Improved declarative memory consolidation in children compared with adults. Sci Rep 10, 9979 (2020). Retrieved from https://doi.org/10.1038/s41598-020-66880-3

Potkin KT, Bunney WE Jr (2012) Sleep Improves Memory: The Effect of Sleep on Long Term Memory in Early Adolescence. PLoS ONE 7(8): e42191. https://doi.org/10.1371/journal.pone.0042191 

Zobida Islam, Huanhuan Hu, Shamima Akter, Keisuke Kuwahara, Takeshi Kochi, Masafumi Eguchi, Kayo Kurotani, Akiko Nanri, Isamu Kabe, Tetsuya Mizoue, Social jetlag is associated with an increased likelihood of having depressive symptoms among the Japanese working population: the Furukawa Nutrition and Health Study, Sleep, Volume 43, Issue 1, January 2020, zsz204, https://doi.org/10.1093/sleep/zsz204

And some references about circadian lighting

Brown, Timothy & Brainard, George & Cajochen, Christian & Czeisler, Charles & Hanifin, John & Lockley, Steven & Lucas, Robert & Munch, Mirjam & O'Hagan, John & Peirson, Stuart & Price, Luke & Roenneberg, Till & Schlangen, Luc & Skene, Debra & Spitschan, Manuel & Vetter, Celine & Zee, Phyllis & Jr, Kenneth. (2020). Recommendations for Healthy Daytime, Evening, and Night-Time Indoor Light Exposure. 10.20944/preprints202012.0037.v1. 

Cain, Sean & Mcglashan, Elise & Vidafar, Parisa & Mustafovska, Jona & Curran, Simon & Wang, Xirun & Mohamed, Anas & Kalavally, V. & Phillips, Andrew. (2020). Evening home lighting adversely impacts the circadian system and sleep. Scientific Reports. 10. 10.1038/s41598-020-75622-4.

Lockley SW, Brainard GC, Czeisler CA. High sensitivity of the human circadian melatonin rhythm to resetting by short wavelength light. J Clin Endocrinol Metab. 2003 Sep;88(9):4502-5. doi: 10.1210/jc.2003-030570. PMID: 12970330.

Michael S. Mott, Daniel H. Robinson, Ashley Walden,Illuminating the Effects of Dynamic Lighting on Student Learning First Published May 6, 2012 Research Article https://doi.org/10.1177/2158244012445585