THE AGEWELL JOYS OF SUMMER NIGHTS

How’s your sleep been recently?

I seem to sleep for fewer hours during these light-filled nights, which I suspect is how our ancestors also slept. More in the long dark months and less in the white nights of summer. Call it seasonal sleep if you like.

I’ve also been up and about in the dark hours looking for glow-worms (at their most prevalent right now) and generally enjoying summer darkness.  I wrote about the joys of summer darkness recently in The Guardian, for anyone wanting tips on how to make the most of this short, sweet season of warm nights.

So I was intrigued by a new study, published this week, that found night-owl chronotypes seem to have better cognitive ability.  I’m not a natural night-owl, despite often being awake in the night.  But this study is interesting because it goes against all the old tales of ‘the early bird’ generally ‘catching the worm.’  Not necessarily so. Particularly as we age. This study was among those aged 53 – 86 and involved data from almost 27,000 participants: it found that those who were more active into the evenings and beyond performed better on cognitive tests for memory, reaction time and general problem solving.

As the lead researcher said ‘research on younger people indicates that morning types tend to have better health and cognitive outcomes. However, our study suggests that the relationship between chronotype and cognitive performance may change with age.  The findings show that evening types (owls) were associated with better cognitive function in our older cohort, possibly due to changes in circadian rhythms and their influence on brain function as people age.’

So for all you lucky night-owls, enjoy these delicious summer nights in the knowledge that – for reasons we don’t understand – your nocturne-loving biology may also be benefitting your brain.

So how much sleep resulted in the best cognition? ‘Optimal cognitive function appeared among individuals reporting 6–9 hours of sleep,’ says the study. ‘With performance diminishing among those with shorter or longer sleep durations.’ A second cohort – who did less comprehensive tests – showed ‘a relatively stable cognitive function across individuals sleeping 5–9 hours.’

Cognitive drops were most marked among those sleeping beyond 9 hours a night. It’s usually thought that this is because long sleepers may already be unwell.  But bear in mind that these are all averages.  And no human is ‘average.’

And what about the insomniacs and the awake-in-the-middle-of-the-nighters? Well, we can all relax.  This study (robust enough to be published in a top journal) found that there was ‘a minimal decrease in cognitive performance’ but it was so modest that the authors deemed it unimportant, concluding that sleeplessness/insomnia had no ‘significant impact…on the global cognitive z-score.’ So for those of us that like to do a spot of star gazing, or 3 am reading, or midnight glow-worm hunting, we can do so without worrying too much about our subsequent cognition.

However, short sleepers also performed less well.  So if you’re up and about in the night do try and catch up later.

All quite mysterious and described in the study as ‘a nuanced age-dependent impact of chronotype on cognition … implying that the effects of morning-ness on cognitive health may evolve over our lifespan.’

Were you once a lark and now finding yourself becoming more owl-ish? Or the other way round? Let us know if you’ve noticed any change in your chronotype over time.

And if you’re out and about after dark do keep an eye on the sky.  The few weeks on either side of the Solstice are the best time to spot noctilucent  clouds – extraordinary shimmering concoctions of wispy clouds that glow in the dark (as in the picture).

Another fascinating study on night and darkness, again published in a top journal, also caught my eye recently. Some of us may be enjoying these long light nights, but when we sleep we need absolute darkness. I’ve been wearing my eye mask nightly to prevent 4am awakenings as the sun pushes through the gaps around my bedroom blinds.

This study found that even very low levels of artificial light-at-night can have a damaging effect on our metabolic health.  For this study, 85,000 people wore light meters round the clock for a week. During this time the light meters registered the amount of light each individual was exposed to. The health of these people was then tracked for 8 years.

The results were clear: the brighter the light in the bedroom between 12:30 am and 6 am, the greater the chance of developing type 2 diabetes.

But what struck the researchers most was how little light was needed to affect metabolic health. As little as 1 lux of light each night seemed to accelerate the risk of type 2 diabetes. The light on a full moon night is around 1 lux, by the way. This tells us how sensitive we are to the smallest amounts of light from TVs, lamps, clocks, light seeping under doors and through flimsy curtains.

This experiment was done before LED lighting became as widespread as it now is.  Experts think that if it was repeated, the results would be even more alarming. Night light has also been linked to obesity, heart disease, psychiatric illnesses, and certain cancers (especially breast and prostate).  How so? No one really knows, but some speculate that night light disrupts melatonin production and that melatonin plays a vital role in helping us fend off these particular diseases. Most of which we become more vulnerable to as we age.

So try and sleep in pitch darkness. And if outside LED lighting is making this impossible, lobby your council to turn its lights off at night. Take a look at the work of the International Dark Sky Association to discover how you can help return our night skies to the inky purity we evolved with.

And if you read my Guardian piece I linked to  earlier, you’ll see that I interviewed a psychologist who studies the effects of the night sky on our mental health.  People who are regularly and safely out at night, he told me, seem to be happier. There’s something about the night sky, about the darkness itself, that we find relaxing and rewarding.

So make time this summer, to enjoy the dusk, sunsets, the softly darkening sky, August’s meteor showers, the last months of Sirius, full moons and new moons, moths, bats, owls, night-blooming flowers and – of course – glow worms.  Who knows, you might even feel happier.

And if you need help, there are three apps I love: Stellarium will point out everything in the night sky; Gojauntly will find a gorgeously green walk of whatever distance you fancy, wherever (in the UK) you are; and the Merlin bird app will identity all the strange bird sounds – and reassure you that the blood-curdling scream you just heard is not a murderer but a Barn Owl! All are either free or very low cost.

This is our last post until September when we’ll be back with all our usual insights, observations and tips for ageing well.  But I thought I’d leave you with a few of the podcasts and articles that have most intrigued me over the last few weeks – just in case you need something to listen to or read on your summer holiday.

First up, this inspiring piece on the significance of learning a language – and why it’s never, ever too late.  I’ve been learning French forever, but this piece has inspired me to learn a little bit more diligently.

Second up, many of the practises and habits of sleep and insomnia that I explored in Sleepless  are investigated and confirmed (with some extra bits and pieces) in this wonderful podcast from All in the Mind.  Yes, it’s normal to wake up throughout the night. Yes, get up and do something after 10-15 minutes of being awake. Yes, stress feeds and fuels insomnia (so tackle that first). And so much more sound and sensible advice that completely resonated with me.

I thoroughly enjoyed this New York Times article on the power of smell and why we should all be mindfully sniffing every day (yes, a pet subject of mine, but it’s such an enjoyable way to self-care, as they say!)

One of the most fascinating podcasts I listened to in the last month was this interview with Dr Gabrielle Lyon on the subject of muscle health for long life. It’s lengthy but interesting – she advises us all to eat more protein and to build muscle via resistance training.  Muscle health (not size), she explains, is vital for ageing well.  Another incentive, should you need it, to persevere with the weights.

Not yet started a resistance programme? For anyone who’s reached their 50s and not yet fully embraced building muscle and fitness, this podcast  from Dr Peter Attia is an excellent summary of how to start – and why it’s never too late to begin a strength and fitness programme. More importantly, he pays specific attention to why avoiding injury is paramount, and how to stay injury-free.

Lastly, if you’d rather hear my dulcet tones talking about walking or optimising and overcoming insomnia, these are a couple of my most recent  podcast interviews.

There’s still time to book tickets to my talk at the Edinburgh Festival (or my co-hosted night walk, for that matter), otherwise come and find me at the 75^th anniversary of the Cheltenham Literature Festival on 10th October. I’ll also be talking in Mayfair, London (9^th October), Oxford (8^th October), Putney London (3^rd October),  and Steyning, West Sussex (16^th October). Ticket links coming in September, but make a note in your diaries now – it would be lovely to see you!

Have a wonderful summer!

Annabel