Sunlight and Other Secrets for Better Sleep

Sunlight and other secrets for better sleep - Image credit Mak Flex

In this blog from the Neuroleader Academy in which we discuss the latest learnings from neuroscience and how to integrate them into everyday life for wellbeing and performance, Deborah Hulme explores how to encourage sleep and discusses the surprising role of sunlight for better sleep and improved personal energy.

Sleep is an invaluable contributor to personal energy

It perhaps goes without saying that sleep is an invaluable contributor to personal energy, so it’s worth spending some time focusing on how we can achieve better sleep.  Many of us suffer from interrupted or fitful sleep at certain moments in life and sometimes, as we age, restful, non-interrupted sleep has a tendency to become more difficult.  If we want to maintain or increase our energy then, it is important to better understand the role of sleep as well as how to encourage sleep and more regular sleeping patterns.

The amount of sleep required differs from person to person

The amount of sleep required differs from person to person and the best way to find out is via trial and error, noticing what does and does not work.  The common rule of thumb though for adults is between seven to eight hours of sleep per night, with children generally needing more.

Adults who can thrive on less than six hours a night account for about 5% of the population and have a rare genetic mutation that facilitates short sleeping with no apparent ill effects (Klein, 2019).  Whilst for the rest of us, if we reduce to six hours or less, we start to see the negative impact within a few days as our performance drops to that of a person who has not slept for 48 hours (Van Dongen, Maislin, Mullington and Dinges, 2003).

Sleep enables the brain to restore itself

As we sleep certain areas of the brain are more active than when we are awake.  Sleep enables our brain to restore itself, consolidate memories and complete a toxin wash, flushing out natural toxins to bring brain toxicity back to healthy levels (Xie et al., 2013).

It also works to make sense of what we do, consolidating our learning so that on waking we have access to insights and answers that were not there before.  Also known as those ‘aha’ or ‘eureka’ moments.

Lack of sleep impairs our logical reasoning, decision-making, memory and creativity

In contrast, lack of sleep impairs our logical reasoning, decision-making, memory and creativity whilst increasing impulsiveness and poor judgement.  In addition, those of us who do engage in 5hrs or less of sleep per night have a 50% chance of being obese.  This being due to a connection between sleep loss and the release of the hunger hormone ghrelin, which directs us to take in more sugar and carbohydrate when tired (Taheri et al., 2004).  There are many good reasons to cultivate healthy sleeping habits. So, what can we do to improve how we sleep?

Aligning our natural rhythms is an important first step to better sleep

We can start by aligning with our natural rhythms, particularly the Circadian and Ultradian rhythms.  Here we’ll focus on our Circadian rhythm, which is the biological system that, among other things, controls our sleep/wake pattern over a 24-hour period.

The Ultradian rhythm we experience throughout the day as high and low-frequency periods of brain activity and this is explored in other materials and podcasts we have available.

Different systems of the body follow the Circadian rhythm, all synchronized with a master clock in the brain, a group of neurons which are located above the roof of the mouth.  These neurons are heavily influenced by, and sensitive to, light, particularly sunlight, which operates our internal cellular timer and is the reason why the Circadian rhythm is tied to the 24-hour cycle of day and night (Blume, Garbazza and Spitschan, 2019)

Bright morning light stimulates our system to produce energy-boosting cortisol

Bright morning light stimulates our system to produce cortisol, a hormone that regulates different processes throughout the body, including metabolism and the immune response, as well as playing an important role in helping the body respond to stress.  Cortisol release makes us more alert with enough energy to get up and face the day.

Morning light also signals to our internal clock to release sleep-inducing hormones at bedtime

However, morning light also signals to our internal clock to release a different hormone, melatonin, about 12-14 hours later.  Natural melatonin, released from the pineal gland in the middle of the brain, is essential for sleep and establishing stable sleep/wake patterns.  This rhythm of cortisol and melatonin release happens within all of us continuously and automatically.  It is when the rhythm is out of sync that it adversely impacts our ability to sleep (Segal et al., 2011)

Our internal Circadian clock responds best to sunlight.  The more we can view sunlight, even sun behind cloud early in the day, the more we activate the cortisol pulse for increased alertness and activity, whilst at the same time setting the timer for later melatonin release to aid sleep. It’s considered by researchers to be 50 times less effective to view sunlight through a window.  and even internal house or office lights do not have the same impact, although bright LED lights are said to be the closest to natural sunlight.

Just a brief exposure to morning light is all that is required

It does not take long for cortisol to flow and the timer to set, an estimated two to three minutes when in bright sunshine and up to 15 minutes if there is heavy cloud.  The key is to obtain appropriate light exposure before the Circadian ‘dead-zone’ which is said to be around the middle of the day between 10am and 4pm when light has no impact on our internal clock. As the day draws to a close and the sun starts to set, our clock starts to adjust for the on-set of rest and sleep.

Dependent on the time we take in our morning light, we can adjust our timer for natural melatonin release backwards or forwards, so impacting our sleep pattern.

Bright light in the evenings hampers our ability to sleep

As late evening approaches, from around 8pm, the more we expose ourselves to bright light, particularly blue light emitted from digital screens such as TVs, computers and phones, the more we stimulate ourselves into wakefulness, thus hampering our ability to sleep.  It’s far better to keep the lights low and wear blue blockers – glasses designed to block blue light from reaching the eyes – if needed, post-8pm.

For night-shift workers reducing morning light to a minimum is key to better sleep

As we all have different light exposure needs, we may need to experiment to find our optimal light timings, however, the foundation of good sleep is a healthy and stable Circadian rhythm.

For those working night-shifts, it’s important to get as much of the evening light as possible, before shift start, whilst reducing morning light to a minimum, which can be helped by wearing a pair of sunglasses if outside at the end of shift.

Other secrets to better sleep

In addition to light management, there are other things we can consider to enhance sleep.  For example, we can consider

  • Reducing caffeine intake, particularly in the afternoon
  • We can avoid exposure to blue light during the evenings post-8pm
  • We can also increase our exercise regime whilst at the same time ensuring we regulate our sleeping, eating and exercise cycles
  • The more we can keep activity timings consistent, the better, and whilst it is preferable to exercise earlier in the day rather than later, if we can only exercise at the end of the day and it has no negative impact on sleep, then that works.
  • Taking a hot shower or bath an hour or two before bed also directs our body towards rest. The water heats our body until we get out of the shower, at which point water evaporation cools the body temperature.  Body temperature has a direct influence on our internal clock and as our body cools, a signal is sent to the brain indicating time to go to bed.
  • And finally do remember to keep the bedroom temperature to around 18 degrees, reducing as much light and noise as possible

Light management, though is perhaps the most powerful.  It works the same way for all regardless of whether we have full sight or not, only becoming ineffective if the eyes have been physically removed (Lickey et al., 1977).

We can all assess whether we need more sleep through observation and listening to our body; are we irritable and/or grumpy for no reason?  Do we feel excessively tired during the day? Or find it hard to drift off or stay asleep at bedtime?

Lack of sleep has a direct impact on personal energy, performance and wellbeing.  It is not a given that we all sleep well, and good sleep often requires direct proactive action if we are to maintain healthy sleep habits.

There are a few of us who do function well as night owls, however, this may be down to genetic difference or it could be because we are simply not getting enough sunlight or bright LED light on waking to set our internal clock for appropriate melatonin release before heading to bed.

In summary, by adopting some of these ideas and supporting healthy sleep habits, we can all work to increase our personal energy levels.

Deborah Hulme is founder of Minerva Engagement and the Neuroleader Academy.  This blog will soon be available to access as a podcast.

To discover more ways of improving personal energy, wellbeing and resilience, get in touch with jennie.flower@minervaengagement.com or sign up to one of our courses, masterclasses or Neuroleader Programmes from the Neuroleader Academy.

References

Klein, A., 2019. DNA mutation lets people thrive on just 4 hours’ sleep. New Scientist, 243(3246), p.18.

Van Dongen, H., Maislin, G., Mullington, J. and Dinges, D., 2003. The Cumulative Cost of Additional Wakefulness: Dose-Response Effects on Neurobehavioral Functions and Sleep Physiology From Chronic Sleep Restriction and Total Sleep Deprivation. Sleep, 26(2), pp.117-126.

Xie, L., Kang, H., Xu, Q., Chen, M., Liao, Y., Thiyagarajan, M., O’Donnell, J., Christensen, D., Nicholson, C., Iliff, J., Takano, T., Deane, R. and Nedergaard, M., 2013. Sleep Drives Metabolite Clearance from the Adult Brain. Science, 342(6156), pp.373-377.

Taheri, S., Lin, L., Austin, D., Young, T. and Mignot, E., 2004. Short Sleep Duration Is Associated with Reduced Leptin, Elevated Ghrelin, and Increased Body Mass Index. PLoS Medicine, 1(3), p.e62.

Walker, M. and van der Helm, E., 2009. Overnight therapy? The role of sleep in emotional brain processing. Psychological Bulletin, 135(5), pp.731-748.

Corsi-Cabrera, M. and Poe, G., 2014. The role of sleep in processing emotional and contextual information: from mechanism to impact on everyday life and emotional health. Experimental Brain Research, 232(5), pp.1399-1401.

Anderson, K. and Bradley, 2013. Sleep disturbance in mental health problems and neurodegenerative disease. Nature and Science of Sleep, p.61.

Blume, C., Garbazza, C. and Spitschan, M., 2019. Effects of light on human circadian rhythms, sleep and mood. Somnologie, 23(3), pp.147-156.

Zisapel, N., 2018. New perspectives on the role of melatonin in human sleep, circadian rhythms and their regulation. British Journal of Pharmacology, 175(16), pp.3190-3199.

Jamrozik, A., Clements, N., Hasan, S., Zhao, J., Zhang, R., Campanella, C., Loftness, V., Porter, P., Ly, S., Wang, S. and Bauer, B., 2019. Access to daylight and view in an office improves cognitive performance and satisfaction and reduces eyestrain: A controlled crossover study. Building and Environment, 165, p.106379.

Segal, A., Sletten, T., Redman, J., Lockley, S. and Rajaratnam, S., 2011. M-J-081 ACUTE ALERTING EFFECTS OF DAYTIME EXPOSURE TO SPECIFIC WAVELENGTHS OF LIGHT. Sleep Medicine, 12, p.S44.

Zhu, L. and Zee, P., 2012. Circadian Rhythm Sleep Disorders. Neurologic Clinics, 30(4), pp.1167-1191.

Lickey, M., Wozniak, J., Block, G., Hudson, D. and Augter, G., 1977. The consequences of eye removal for the circadian rhythm of behavioral activity inAplysia. Journal of Comparative Physiology ? A, 118(1), pp.121-143.