Sleep well last night? If so, you are apparently in a minority. The American Sleep Association, the Sleep Foundation and the American Association of Sleep Technologists all claim that over half of adults have a sleep disorder (ie 1).
These dogs could just be barking in the night, but the only slightly less opaque National Highway Traffic Safety Administration tells us that 1 in 25 drivers fall asleep at the wheel (2), and that this accounts for nearly 100,000 crashes a year (3). So there does seem to be a real problem.
Stress, pain, poor sleep hygiene, crying children and noisy neighbours make sleep difficult for many. Others find it hard to fit in with the socially prescribed 8 hours.
Many pre-industrial societies had a first sleep from dusk to circa midnight and a second sleep from the small hours till dawn (4, 5), and some say that this may be a more natural pattern.
But then there are the siesta cultures. Greece, Israel, Nigeria and the Hispanic nations have a traditional sleep period at mid-day, although Mexico ‘abolished’ the siesta in 1944 as a mañana war measure to save car tires … Sleep behaviour is clearly culturally plastic, and we are an adaptable species.
But still, consider all those insomnicidal traffic accidents. Too many people clearly have difficulty staying asleep, staying awake and staying alive. What can be done?
There is a lot to be said for waking at dawn’s first light. If you haven’t slept well and are finding it hard to get the world into focus, there’s nothing like bright sunlight to dispel the morning mist (6). As you feel your pupils constricting, the photopigment in your retinas bleaching and the initial hypersensitivity to bright light fading, you are recapturing a righteous circadian rhythm that helps most folk feel more alert in the day and sleepier at night (7, 8).
Morning light suppresses melatonin synthesis in the pineal gland (9), and kick-starts the sympathetic nervous system (10). This is one reason why coronaries often arrive with the cornflakes (11). The ridiculously high (12) glycemic index of many breakfast cereals is another (13-15).
But the sunlight is likely re-setting your circadian clock in other ways too. Exposure to sufficiently intense sunlight triggers D synthesis, and new research suggests that this hormone may have a significant and separate impact on sleep.
A series of clinical investigations are beginning to show that higher D levels are associated with shorter sleep latency and better sleep quality (16), and lower D levels are associated with shorter sleep, and obstructive sleep apnoea (17-19). The sleep apnoea is a bit of a red herring, in my view, as it is more common in the obese who have lower D levels due inter alia to volumetric dilution (20).
One group found that D supplements improved sleep duration and quality in sleep disorder subjects (21), another team found similar results giving D-enriched milk and yoghurts to insomniacs (22). One meta-analysis (9 trials, 9367 subjects) found that sleep disorder subjects had lower D levels than sound sleepers (23), and a later and broader meta-analysis (25 trials, 3603 subjects) produced similar findings (24).
So is it time to re-position D as a sleep aid? Not quite yet, I think. The nature of the relationship between D and sleep health is very unclear (25, 26). It might involve causation, reverse causation, bidirectional causation or simple association.
Sleep disorders, by creating daytime sleepiness, tend to make outdoor activity and sun exposure less likely. D depletion increases the risk of chronic diseases from osteoporosis to skeletal myopathy (27), making outdoors activity more challenging. D depletion might cause immunological changes leading to tonsillar hypertrophy (28) and thence sleep apnoea.
It could disrupt sleep by contributing to chronic pain syndromes (29), including the pain and discomfort of fibroids which are also associated with D depletion (ie 30). It might cause insomnia via central mechanisms including increased levels of neuroinflammatory compounds (31, 32), reduced synthesis of melatonin and direct actions at D receptors in areas of the brain involved in sleep regulation (33, 34).
Or it could simply be that more of us in industrialised societies are spending more time indoors. Office space and domestic environments combining low levels of physical exercise, chronic stress and addiction to LCD screens and caffeine create D depletion and sleep problems; so D and sleep may not be directly linked at all.
I tend to think that D supplements may be helpful in improving sleep in those with severe D deficiency and related symptoms such as fibroids or fibromyalgia, but this is based on limited professional experience and a single meta-analysis (35). And for biohackers and keen self-medicators, there is a practical problem. Even if D supplementation does improve sleep in some subjects, the different interventions used in the relatively few published trials make it difficult to make any clear recommendation about dose or timing.
But we have to start somewhere.
In the same way that trans-dermal melatonin should be taken as your mitochondria dip down into the dark phase (ie in the evening), D supplements might be expected to work best when taken at the start of the light phase (ie in the morning). As oral supplements are generally best absorbed when co-ingested with food, D with your eggs and bacon seems reasonable.
Food is not required if your D is in an oral bioadhesive strip, allowing more flexible timing. This would suit anyone on an intermittent fasting schedule.
And the dose? 5000 IU/day might frighten the regulatory horses (especially the timid Danes), but is well within evidence-based safety limits, even more so if combined with vitamin K (36).
Self-experimenters might try combining those 5,000 IU with 3g of L-glycine, which has documented sleep-enhancing effects (37-39) and a very different mode of action (40, 41), together with a handful of seaweed. Phlorotannins also have sleep-promoting properties(42-46), and as these molecules have such different structures the likely dissimilar mechanisms may well be additive or supra-aditive.
These supplements may be particularly helpful in the elderly, whose sleep patterns are the most fragmented and whose generally declining quality of life is considered normal in our sickly post-transitional world.
Our elders generally have less exposure to daylight. They are more likely to have chronic health conditions which militate against sound sleep. Furthermore, as the brain ages, the suprachiasmatic nucleus starts to malfunction and both sleep structure and endocrine cycles (such as melatonin) start to fade (47).
The elderly are also more likely to be on medications which induce day-time sleep and make night-time sleep more difficult; and more likely to be over-medicated in general (48, 49). So as the shadows lengthen, they take more sleeping pills (50, 51).
For those who can’t get enough Z’s Big Pharma provides Zaleplon, Zolpidem, traZodone, triaZolam, temaZepam, esZopiclone and a diZZying range of adverse effects. These include cognitive impairment, addiction (52-55), withdrawal problems including seizures and delirium (56), and increased risk of dementia and death (56, 57).
You would be better off with trans-mucosal melatonin at night, D at dawn and lots of daylight. This regime has side effects too, but they are entirely positive.
Finally, there’s more to daylight than UV & D. There is also IR and near-IR.
Our species evolved with a good deal of exposure to daylight. Hunting, gathering, foraging and other general activities would have entailed perhaps 10 hours of exposure / day. We now live and work indoors and travel in closed vehicles, and our exposure to daylight is somewhere around 10 hours / week (58, 59). This likely has implications for our health because near-infra-red light, a component of daylight but not of artificial lighting, is critical for the intra-mitochondrial synthesis of melatonin (60, 61).
The authors of the last two papers distinguish between circulatory melatonin produced by the pineal gland (the ‘hormone of darkness’), and intra-cellular melatonin, which is a daylight hormone. Intra-cellular melatonin, which seems to be rather more important for our health, cannot be affected by supplementation. It is, however, increased by exposure to the near-infra-red wavelengths in daylight.
This is a truly fascinating area of research.
Red light penetrates deep into our tissues (62). Red light photons modulate electron transfer in the oxidative phosphorylation chain and enhance mitochondrial function, increasing ATP and melatonin production (63-69) in what is probably a mitohormetic response (70, 71). This is how the new near-IR lasers, such as Lyma Life’s hand-held device, trigger skin healing and regeneration (72).
But IR probably does more than that. It is likely one reason why the affective disorders show a degree of seasonality (ie 73-75) and sensitivity to daylight levels (76), and why sun-bathing may be useful in the treatment of at least some types of depression (77). Increased melatonin levels reduce neuro-inflammation (78), creating neuro-protective and anti-depressant effects (79).
A recent UK Biobank study of over 500,000 subjects found that every additional hour spent outside during the day was associated with lower odds of neuroticism, unhappiness, major depression and anti-depressant use. And fewer sleeping problems (80) …although for possibly evolutionary reasons (the Savannah effect), the therapeutic effects of sunlight may be less in more intelligent individuals (81).
Some suggestions …
Do – Check your D status and if low, supplement. Zinzino offers a highly accurate D-test for home use, at discounted rates. Be diurnal. Darkness at night and daylight during the day makes good evolutionary sense.
Don’t – Use LCD screens at night. Blue light degrades mitochondrial function in the retina, reducing melatonin synthesis and potentially triggering the programmed inflammatory form of neuronal death known as necroptosis (82, 83). This is more likely to cause problems if you’re also eating an industrial, pro-inflammatory diet. Conversely, the Health Protocol should be protective.
Do – If you have to use a laptop or mobile during the hours of darkness, switch to an amber/red screen display. Put a red lamp by your bed; in our DNA-hacked future, blue light will mean something very different (84).
In the meantime sleep well, sweet dreams, drive safe.
Next week: Methylation, acetylation and the epigenetic diet.
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