The benefits of finding and obeying your natural ‘sleep window’

Each of us has a personal “sleep window” – a period of time during which our body wants and expects to sleep.

But because of a range of factors, which include everything from electric lighting to the use of smart technology devices, many of us have lost track of what our sleep window actually is.

Lack of sleep has become an epidemic in the western world, according to sleep and fatigue specialist Dr Katharina Lederle, who warns that getting adequate, refreshing sleep is crucial for our physical health, cognitive performance and emotional wellbeing.

“More often than not, a combination of different factors comes together in a way that results in us either not sleeping enough or experiencing poor sleep.

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“It’s important to note that, while some reasons are under our control, others just aren’t. And the way all these factors and causes play out can be different for each one of us,” she says, adding that stress, work demands, family life, social engagements, lifestyle, light exposure, health, sleep disorders and socio-economic status can all affect how well and how long we sleep.

Lederle, an international expert who advises airlines, emergency helicopter services and corporations within the petrochemical, mining and pharmaceutical sectors, points to a 2013 sleep survey of six western countries, including the United Kingdom, the United States and Germany.

The study found that in the three countries mentioned, only about 40 per cent of people said they got a good night’s sleep every night, while more than 50 per cent believed inadequate sleep affected their mood and performance.

So what should we do?

Meet the conductor

Each of us has an internal body clock, which is a group of neurons called the suprachiasmatic nuclei (SCN), which sit in a part of the brain called the hypothalamus.

“I like to compare the SCN to the conductor of an orchestra, setting the rhythm for the rest of the body,” explains Lederle. “This is important because each organ, and in fact most of our cells, has its own clock and would function according to its own rhythm if it wasn’t for the internal clock,” she says.

She compares our internal clock to an orchestra: each player has his or her own rhythm, and without the conductor they wouldn’t play in unison.

“We simply wouldn’t be able to function in a way appropriate to the time of day if it wasn’t for the master clock and its synchronising abilities,” she explains.

However, because we are individuals, each of our clocks are also slightly different, so that each of us has a very individual sleep “time”, or sleep window, says Lederle.

A good example is the phenomenon of “larks and owls”: some people must go to bed early, while others who feel compelled to stay up late.

“Sleep times are different for different people,” she says, adding that modern life, with all its distractions – from electric light to tech devices – can encourage us to stay up far beyond the beginning of our personal sleep window.

But the quality of sleep we get, says Lederle, is determined by how much and how often we sleep within our personal sleep window. She believes we sleep better if we honour it.

“We are the only species which can push back our sleep times, and that’s what a lot of us are doing.”

The problem is that as adults we can control when we go to bed, but because of work and commute commitments, our wake-up times are usually much more regulated, resulting in our sleep time being abbreviated.

Recognising your window

While some people may have an inkling about where their body’s sleep window actually is, others have spent so many years ignoring it that they no longer have any idea what it might be.

So Lederle has created what is essentially a five-night “sleep cleansing” regimen to help us pinpoint our individual sleep window (see panel).

Once the boundaries of your sleep window have been established, she advises, stick to it as much as possible and also implement her suggested “scaffolding” around healthy sleep (see panel) to structure your day in a way that maintains a healthy sleep rhythm.

“The more regular you are in maintaining your sleep window, the more your body gets into the rhythm of it,” she says, adding that the occasional exception should not have an adverse effect.

None of this means you’ll never again experience a sleepless night, she says, but it does minimise the risk of insomnia.

However, to facilitate this concept fully, says Lederle, there needs to be a shift in the way society perceives sleep, and work:

“Today it’s all about work and what is forgotten is the human need for sleep. “We need to pay attention and allow people to sleep when it is the best time for sleep.

“I believe as a society we need to shift to a more flexible way so that people can have the sleep time that is suitable for them.”

• Sleep Sense – Improve Your Sleep, Improve Your Health by Dr Katharina Lederle, Exisle Publishing, €18.20

How to Find Your Sleep Window

(1) Plan ahead. Decide when to run your experiment, because you will need five nights when you are not under pressure to be anywhere in the morning – a stay-at-home holiday period is a good time to do this.
(2) Consume no more than one or two cups of coffee or tea in the morning, and none after 2pm. Cut out alcohol.
(3) As evening arrives, keep your environment dimly lit – allow natural light conditions to prevail or use the dimmer switch.
(4) Turn off your phone, tablet, laptop or other device two to three hours before bedtime. If possible, turn off the TV as well, as this is a form of external stimulation
(5) When you feel ready for bed, go to bed. You will need to do this several nights in a row before you really get a fix on your personal sleep window.
(6) Only on night five should you take a note of your bedtime and wake-up time, because this is your sleep window. Try to stick with it as much as you can, but remember, this does not mean you have to endure an inflexible bedtime routine.
(7) However, if you find that your natural sleep window has a late beginning – for example, 1am – and work demands that you be up by 7am, try to bring it back a little by dimming the lights earlier in the evening and cutting back on your use of devices.

Scaffolding for healthy sleep

– Make sleep your priority.
– Have a calm, cool, comfortable sleep environment. Try to keep your bedroom temperature to 16-18 degrees.
– Have a bed and bedding that you feel comfortable in. Invest in good pillows.
– Consume no more than a couple of cups a coffee early in the day and none after than 2.30pm.
– Deal with your stress.
– Have regular mealtimes. These will help your internal clock to stay with the 24-hour light/dark cycle.
– Stay hydrated but reduce your intake of liquids in the evening to help minimise overnight toilet use. If you need to get up more than once during the night to use the bathroom, try to stop having liquids altogether one hour before bedtime.
– Lower the lights and minimise blue light exposure (from LED devices, including smartphones, tablets, laptops and close-range TVs). These act like mini-suns, increasing your alertness and affecting your internal clock by suppressing the release of melatonin. Aim to turn them off three hours before bedtime.
– Reduce alcohol intake. Drinking regularly in large amounts or using alcohol as a sleep aid can have adverse effects on your sleep, and health in general.
– If you smoke, ensure you have your last cigarette at least two hours before going to bed. Nicotine is similar to caffeine in that it acts as a stimulant, making it harder to fall and stay asleep.
– Wind down in the evening by doing something that's relaxing and nurturing.
– Exercise regularly, but not within the last three hours before bedtime, otherwise it might negatively impact your ability to fall asleep by raising your body temperature too much.
– Have a light and early dinner. This ensures your digestive system is not still working when it's time to sleep.
– Have a regular bedtime, ideally in tune with your internal clock, and regularly go to bed within a 30-minute window of this time. Turn off your phone or put it on silent to minimise the risk of being disturbed during the night.
– If you wake up during the night and struggle to get back to sleep, stay in bed. Avoid using your phone, tablet or e-reader. Instead, try adopting an accepting attitude while allowing yourself to be awake rather than getting worked up and frustrated with the situation.