Sleep is not wasted time

For much of my working life, I slept only five or six hours a night.

Not because I needed less sleep than other people, but because I always believed I had more important things to do. I usually had several irons in the fire, and sleep felt suspiciously like lost time.

I may even have regarded the ability to function on little sleep as a sign of strength.

I could sleep when I was dead.

The problem was that my body never seemed to receive that message.

I have almost never been able to go to sleep before midnight. Even when a difficult working day ended just before midnight, I could not simply crawl into bed and switch myself off.

I needed time in between.

Not necessarily to do anything useful or important. I simply needed some hours that belonged to me—when nobody expected an answer, a decision or a solution.

Sometimes I watched television without really watching it. My mind would continue working, sorting through the day, thinking about my life or wandering into entirely unrelated territory. It was my private decompression chamber.

Then the alarm went off and another working day began.

This could continue for days, sometimes longer, until my body finally sent me the bill. Then I might sleep for twelve hours. I called it sleeping in. In reality, I was making a late payment on a sleep debt for which my body had temporarily extended the credit.

A Family of Night Owls

My children and I are all evening types—night owls rather than early birds.

Whether this has anything to do with the traits of ADHD that I recognise in all of us, I do not know. Chronotype is influenced by biology, habits and environment, and probably by some mixture of all three. There may be an association between ADHD and delayed sleep timing, but a late bedtime is not a diagnosis, and a family resemblance is not a medical test.

One of my sons stood out when he was young. He had considerable attention difficulties at primary-school age, but sleep was another matter.

On Saturday evenings we often watched a good film together, and everyone received a bag of sweets. He was absolutely determined to stay awake as long as the rest of us. Yet he was almost always asleep before he had made any serious progress into the bag.

His pattern later changed, and today he is every bit as much a night owl as the rest of us.

Being a night owl has never carried much social prestige. Society tends to admire the person who is bright-eyed and productive at six in the morning rather more than the person having his best ideas after midnight.

But biology is not a moral competition. Waking early does not automatically make someone disciplined, and sleeping later does not automatically make someone lazy.

The Third of Life We Know Least About

We know a great deal about what we do while awake. We work, talk, eat, move, argue, love and waste time.

Yet we know surprisingly little about the roughly one-third of life during which we are largely unconscious.

Perhaps that is because sleep looks like inactivity. A person lies motionless with closed eyes and appears to have taken temporary leave from life.

But the brain is not switched off, and the body has not placed an “out of office” notice on the door.

The night is organised into repeating cycles. Sleep is usually divided into three non-REM stages—N1, N2 and N3—and REM sleep.

N1 is the transition from wakefulness into sleep. N2 is established sleep and usually occupies the largest part of the night. Heart rate and breathing become slower and body temperature falls.

N3 is deep, slow-wave sleep. Large, slow electrical waves become prominent in the brain. This is the most restorative and physically renewing phase of sleep, where the body and brain slow down to their lowest level of activity.  It is harder to wake someone from this stage, and a person awakened abruptly may be confused and heavy-headed for a while.

REM sleep is different. The brain becomes highly active, the eyes move rapidly, dreams are often vivid and most skeletal muscles are temporarily inhibited, probably preventing us from acting out our dreams.

Deep sleep is more prominent earlier in the night. REM periods tend to become longer toward morning.

This is why seven hours of repeatedly interrupted sleep may not feel as restorative as seven reasonably continuous hours. The number on the clock matters, but so do the continuity, timing and structure of the sleep.

Two Systems Argue Over Bedtime

I used to think that people fell asleep when they became tired enough. That is only half the story.

Two main forces influence when we feel sleepy and when we can actually fall asleep.

The first is sleep pressure. It gradually increases from the time we wake up

. Adenosine is involved in this process and accumulates in the brain during wakefulness. Caffeine blocks adenosine receptors, allowing us to feel more alert without removing the underlying need for sleep.

The second force is the body clock. It synchronises our physiology with the cycle of day and night. Light is one of its most powerful timing signals.

Melatonin is better understood as a darkness signal than as a knockout drug. Its evening rise tells the body that biological night is approaching. Cortisol follows a different rhythm and normally rises toward morning, helping prepare us to wake.

Sleep pressure can therefore be shouting after a long day while the body clock is saying, “Not yet.”

That may explain why we can be exhausted in the late afternoon and strangely alert again in the evening. It also explains why a short nap may help, while a long or late nap can remove enough sleep pressure to interfere with the coming night.

Jet lag is another example. The body can travel from Iceland to Thailand in less than a day, but the internal clock takes much longer to adjust.

By the time you land in Bangkok, you have arrived – but your body clock is still on the way.

.A Night Owl in an Early-Bird World

People have different natural preferences for sleep timing. Some become sleepy early and wake early. Others come alive as evening approaches, even when the next morning demands an early start.

A night owl can adopt a schedule, but he does not necessarily become a morning person simply by buying a louder alarm clock.

I find the possible link between ADHD traits and delayed sleep interesting, but I would not make more of it without knowing for sure. A late rhythm does not prove ADHD, and neither a child nor an adult should be diagnosed from family anecdotes.

For me, a more immediate question is this: Why have we so often needed those quiet hours after midnight to come down from the day and finally be alone with our thoughts?

The Icelandic light does not make matters simpler. Summer nights barely become dark, while winter mornings lack strong natural light and the days are short. Phones, computers and televisions add another layer. The brightness, duration and timing of light all matter.

Light is not the whole explanation, but it is one of the strongest tools the body clock uses to tell time.

When the Body Collects the Debt

Sleep restriction is not a single missing piece that can be replaced intact at the weekend.

When sleep is repeatedly shortened, attention and reaction time suffer. Memory may become less reliable, mood more fragile and judgement poorer.

The treacherous part is that we do not always recognise the extent of our own impairment. A person who has been tired for years may begin to think that this is simply what normal feels like.

Recovery sleep does help. Deep sleep may become more intense after deprivation, and REM sleep can rebound under some circumstances. But the repayment is not exact. One twelve-hour night does not necessarily erase the effects of a string of short nights.

The body offers credit, but the interest rate may be higher than we realise.

Sleep Ages With Us

Sleep changes with age. It commonly becomes lighter and more fragmented, deep sleep decreases and awakenings become more frequent. A person may spend eight hours in bed without sleeping for eight hours.

Many people also become sleepy earlier and wake earlier as their circadian timing shifts forward.

A man in his late sixties who wakes at five in the morning is therefore not automatically depressed, although early waking can also occur with depression. Context matters.

Night-time urination becomes more common as men age. An enlarged prostate may contribute, but it is not the only explanation. Bladder function, evening fluid intake, medication, sleep disorders—including sleep apnoea—and other medical conditions may all play a part.

The real damage to sleep may occur after the visit to the bathroom, when returning to sleep becomes difficult and the remaining night breaks into fragments.

Men also commonly have erections during sleep, particularly around REM periods. These are not necessarily connected to conscious sexual arousal. They are simply another reminder that the body continues its biological business while the owner is absent.

Sleeping Pills and the Traditional Nightcap

Sleeping medication can be a double-edged sword, especially in older people.

Long-acting benzodiazepines may accumulate more readily and contribute to next-day sedation, impaired balance, falls and cognitive problems. The newer so-called Z-drugs do not remove all those concerns.

This does not mean that every sleep medication is always wrong. It means that sleep is not a simple switch that can be chemically turned off without consequences.

Melatonin may be useful when the main problem involves the timing of the body clock, but it is not a universal solution to chronic insomnia, and its average effect can be modest.

For persistent insomnia, cognitive behavioural therapy for insomnia—CBT-I—is generally considered the first-line treatment. Long-lasting sleep problems also deserve an assessment of the cause rather than an endless renewal of the prescription.

In earlier times, a nightcap was often recommended as the gentler alternative. A small cognac might help a person relax and fall asleep sooner.

Unfortunately, alcohol tends to make sleep more fragmented later in the night and can disrupt REM sleep. Medicine has therefore progressed from the era when the choice appeared to lie between a long-acting sleeping pill and a glass of cognac.

The cognac has not passed the test of time either. A regrettable result in some respects, but there it is.

Thatcher, Churchill and the Four-Hour Night

Margaret Thatcher became famous for reportedly sleeping only about four hours a night.

Winston Churchill is also frequently recruited into the short-sleeper hall of fame, but his arrangement was different. He was known for dividing his sleep and protecting an afternoon nap.

There is an important difference between a divided sleep pattern and obtaining only four hours in total.

Someone who sleeps six or seven hours at night and takes a regular nap may have found a workable arrangement. Four hours at night with an occasional doze is an entirely different proposition.

The fact that Thatcher governed Britain on little sleep does not prove that four hours is a sound recommendation—any more than stories about Churchill prove that cigars, alcohol and afternoon naps form a complete health programme.

Famous people can be historical examples without becoming biological standards.

Then the Caveman Entered the Defence

I have occasionally heard the argument that modern people do not need as much sleep as experts claim.

According to one version, our ancestors had nothing to do after hunting, eating, tending to basic needs and looking after the family, so they simply lay down and slept. Modern lighting, television and phones then robbed us of this natural abundance.

Research on present-day societies living without electricity and in ways closer to traditional hunter-gatherer life suggests a more complicated picture. Their sleep is not necessarily eight uninterrupted hours. It varies with light, temperature, season and social life.

A natural life does not automatically mean very long sleep. Nor does it prove that the rest of us should be content with five hours.

Our ancestors also had to survive weather, predators, conflict and numerous other disturbances unlikely to improve sleep quality.

We may have spent too long searching for one perfect number.

How long do you sleep? When do you sleep? How continuous is the sleep? Most importantly, how do you function when you wake up and during the following day?

Those questions together tell us more than a number alone.

What I Am Trying to Do Differently

I am still a night owl. I still have some of my best ideas when the so-called sensible people have gone to bed. I still find it difficult to move directly from intense work into sleep.

The solution is not to shame myself into becoming a cheerful morning person. It is to stop confusing biology with laziness—and to stop using chronic sleep debt as proof of strength.

That means giving myself a deliberate transition between work and bed, rather than pretending I have an off switch. It means paying attention to morning light, the timing of caffeine, long or late naps and the temptation to extend the evening indefinitely simply because it is finally mine.

It also means taking persistent problems seriously: snoring and possible sleep apnoea, repeated night-time urination, pain, low mood, restless legs, medication effects or insomnia that has taken on a life of its own.

A simple sleep diary kept for two weeks may reveal more than months of vague impressions. For long-standing insomnia, CBT-I offers something more useful than another list of sleep-hygiene commandments.

I once believed that sleep was the part of the day when nothing happened.

Now I know that memory is being processed, body systems are changing rhythm and the internal clock is trying to keep the entire operation together—often while the owner stubbornly refuses to go to bed.

Perhaps we should not ask only how many hours a person slept.

We should ask how he slept, when he slept and how he felt when he woke up.

I can certainly sleep when I am dead if there is nothing else after death.

But I have begun to suspect that good sleep may have quite a lot to do with how I feel until then.