I came across this report last week of a study into sleep-wake cycles. A group of adults were monitored in their normal environments (with electrical lighting, TV and electronic devices) and also had their levels of the ‘sleep hormone’ melatonin assessed [1]. It was discovered that in their normal environment, melatonin secretion was generally delayed at night. Also, at 8 o’clock in the morning melatonin levels were still raised, and remained high for several hours after they got up. High levels of melatonin are good when we want to sleep, but not so good if we want to feel fully energised and ‘raring to go’.
This ‘delaying’ effect on melatonin is not too much of a surprise, as previous research has produced similar findings. In one study, exposure to room lighting prior to bedtime delayed melatonin secretion by 90 minutes on average, and reduced the overall amount of melatonin too [2]. In another study, lights from laptops and tablet devices was also found to suppress melatonin too [3].
The study subjects were then taking camping for a week, with the only light they were exposed to coming from the sun and a campfire. By the end of the week, the study subjects had their sleep ‘synchronise’ with the setting and rising of the sun. The sleep-wake cycle shifted by about 2 hours back (earlier). And in the morning, melatonin levels were found to be low (as they should be).
Getting more natural light during the day is very likely to have been a significant factor here, I think. Melatonin is actually made from the brain chemical serotonin, the production of which is stimulated by sunlight [4].
Could waking up to dawn light also have brought some benefits for the people in the study? It seems so, as ‘dawn simulation’ does seem to have the potential to benefit people. Dawn simulation devices are essentially alarm clocks that use light (rather than sound) to wake people up (though some devices combine the two). Dawn simulation has been found to help people suffering from seasonal affective disorder (‘winter blues’) [5-7] and in particular seems to help people get up in the morning [8].
This could be of particular use in the winter, as many find that getting out of bed and on with the day on dark mornings is a struggle. Other research in those prone to problems in the winter found that dawn simulation can improve energy on waking, as well as mood, productivity and quality of sleep [9]. Dawn simulation alarm clocks are widely available from manufacturers such as Philips and Lumie.
It’s generally impractical for many of us to live ‘under canvas’, but there are steps we can take to give our brain the best chance of being ‘in sync’ with natural sleep cycles. If I were to boil my advice down into simple pieces of advice, I would suggest:
- Getting some decent natural light exposure during the day.
- Keep light exposure from room lighting and devices as low as possible in the evening
- The use of a ‘dawn simulation’ alarm clock in the morning
All of these are more important in the winter, as this is the time people tend to struggle most with mood and sleep issues.
References:
- Wright KP, et al. Entrainment of the Human Circadian Clock to the Natural Light-Dark Cycle Current Biology, 01 August 2013
- Gooley JJ, et al. Exposure to room light prior to bedtime suppresses melatonin onset and shortens melatonin duration in humans. J Clin Endocrinol Metab 2011;96(3):E463-72
- Wood B, et al. Light levels and duration determines the impact of self-luminous tablets on melatonin suppression. Applied Ergonomics 2013;44(2):237-240
- Lamber GW, et al. Effect of sunlight and season on serotonin turnover in the brain. The Lancet 2002;360(9348):1840-1842
- Avery DH, et al. Dawn simulation and bright light in the treatment of SAD: a controlled study. Biol Psychiatry 2001;50:205-216
- Avery DH, et al. Dawn simulation treatment of winter depression: a controlled study. Am J Psychiatry. 1993;150(1):113-7
- Avery DH, et al. Dawn simulation compared with a dim red signal in the treatment of winter depression. Biol Psychiatry. 1994;36(3):180-8
- Avery DH, et al. Is dawn simulation effective in ameliorating the difficulty awakening in seasonal affective disorder associated with hypersomnia? J Affect Disord 2002;69:231-236
- Norden MJ, et al. A controlled study of dawn simulation in subsyndromal winter depression. Acta Psychiatr Scand. 1993;88(1):67-71
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I recommend f.lux (justgetflux.com) for your computer – it automatically dims down the screen in the evening, softening the ‘sunlight’ glow which is only appropriate in the daytime. This facilitates the transition to lights out when you go to bed.
Great post Dr. Briffa. Ironically, although I specialize in natural medicine for urological conditions, my latest post was on sleep as well. I hope you enjoy the read and excuse the grammatical errors and typos 😉 – work in progress.
http://drgeo.com/my-sleep-deprivation-experience-why-sleep-is-important
I went on a weeks camping trip in May and noticed the same sleep improvement dramatically and felt so good for it. I was exhausted by 9-9:30pm and was asleep by 10pm most nights, rock & roll i know and quite unusual for me.
Back at home It’s so hard to put the laptop down, phone away or turn the TV off as this is often considered downtime but really isn’t.
To try and get away from this disconnect I’ve started to read in the garden (when the weather allows) until it’s too dark too see the pages. Although not as dramatic as the camping trip it has helped me wind down and bring on the sleepy feeling. I wonder if the earthing effect while camping (i walked around barefoot) was also a factor or it was purely the lack of “fake light”?
I’ll have to come up with a new routine in the winter and maybe that will help me take the next step to switching off the TV earlier when indoors?
It is the blue light component that is the worst. Sunlight has blue light only in the morning; in the evening it gets ‘warmer’. Humans have blue light receptors in their eyes so the morning sun can set your circadian rythm.
Blue light in the evening makes a mess of your time setting. Sleep is the first to suffer. But the consequences go way beyond that. Too bad all this I-pod,I-pad stuff emits lots of blue light.
I do use f.lux, but I have set the temperature of the light to 2700 kelvin all day. It takes away 95% of the blue light.
Philips Hue lights are also worth looking at. They are colour variable LED bulbs, and can be controlled by a smartphone app (with timers, proximity etc.) I have two in the living room and another on a timer in the bedroom as a morning alarm. http://www.meethue.com has more information.
All the best,
Graham
Smartphones are as much a problem as the light. I expect Dr Briffa to treat this issus in a future blog.
In short: genetic expression is controlled by the Schumann resonance that comes from the earth’s magnetic field. Electro-magnetic-frquencies (EMF) from you ‘smart’ phone interferes with this resonance, thereby changing you genetic expression.
Couldn’t agree more about the negative affects that computers et al can have on sleep. I can guarantee a poor night by working late, whereas finishing at 9.00pm helps me get to sleep quicker, and that also usually results in a better night.
If it’s been impossible not to work into the late evening for several nights I quite often fall back on Melatonin, and after only a few nights of that regime I find that I’m back on the wagon.
I believe that it could be EMF’s (electrical magnetic fields) that could affect us. Our bodies and the ground are at 10 hertz and electrical items such as appliances, wiring, lights, etc are at about 50 hertz. Wireless devices such as routers, cordless phones, mobile phones (even not in use) and also your TV emit frequencies which are much higher – experts advise that in order to fall into the deep REM sleep which we need for the body to regenerate.
So, it is particularly important to switch off all appliances and wireless devices which are in the room.
I had a particular problem with memory and discovered that it was worse when sleeping in our bedroom which has a circuit breaker above our bed. We now turn off all wireless devices, turn off and unplug all appliances, mobile phones, we switched to a corded phone and I found good quality protection from EMFs which has greatly improved my memory.
That would, to me, make sense when it comes to turning off lighting, computers, etc and also the earthing effect which Stuart speaks about in his post.