Your Brain Is Drunk. What Sleep Deprivation Really Does to Your Judgment in Hong Kong

By John Corbett | Psychologist | Hong Kong

Picture the scene.

A Tuesday morning in Central, Hong Kong. A senior professional walks into a high-stakes meeting. They're dressed well. They're articulate. They present their analysis confidently. They field questions. They make decisions.

Nobody in the room notices anything wrong.

But here is what the research on sleep deprivation effects on performance tells us might be true about that person — and many of the people sitting around the table with them.

After 17 to 19 hours without sleep, cognitive and motor performance declines to levels equivalent to a blood alcohol concentration of 0.05%. After 24 hours awake, that rises to 0.10% — above the legal drink-drive limit in every jurisdiction in the world, including Hong Kong.

Now do the maths on a typical Hong Kong professional day.

Wake at 6:30am. Work until midnight. That is seventeen and a half hours of continuous wakefulness. By the time that person goes to bed, their cognitive performance has declined to the equivalent of someone sitting at the legal drink-drive limit. And if they slept five or six hours the night before — which, in Hong Kong, is far from unusual — the impairment was already accumulating before they even opened their eyes.

Hong Kong ranks last out of 15 Asia-Pacific territories in healthy living surveys, with residents averaging just 6.5 hours of sleep per night — below what respondents themselves said they needed.

The city that never sleeps is not a boast. It is a public health statistic.

How Sleep Deprivation Impairs Judgment: The Comparison Nobody Wants to Make

When I share this research with professionals in Hong Kong, the reaction is usually somewhere between discomfort and genuine disbelief. Not because they doubt the numbers, but because the implication is so direct and so inconvenient.

We have detailed social and legal infrastructure around alcohol impairment. Drink-drive laws. Professional conduct rules. Cultural norms about drinking before important decisions. If a lawyer appeared at a client meeting having had three drinks, there would be consequences. If a fund manager made a significant allocation decision with measurable alcohol in their system, that would be, at minimum, a serious conversation.

Sleep deprivation produces a functionally identical level of impairment — and we treat it not just as acceptable, but in many professional environments, as evidence of commitment.

The person who worked until 1am and is back in the office at 7am is not considered impaired. They are considered dedicated. There is no breathalyser for sleep debt. There is no legal framework. There is no social norm that flags it as dangerous.

This is, when you sit with it, a genuinely strange state of affairs.

Why You Can't Feel How Sleep-Deprived You Are

If the effects of poor sleep on cognitive function were obvious — if sleep-deprived professionals felt as compromised as the tests show them to be — the situation would at least be self-correcting.

But that is precisely not what happens.

The brain adapts its subjective experience of sleepiness through a process of recalibration — essentially moving the baseline. The performance systems involved in reaction time, executive function, and working memory don't adapt in the same way. They degrade continuously, below the threshold of conscious awareness.

The practical consequence: a person who has been sleeping six hours for months genuinely believes they are functioning normally. They are not. And unlike someone who pulls a single all-nighter — who knows they are impaired — the chronically sleep-restricted person has no internal warning signal.

This creates a self-reinforcing trap. The worse performance becomes, the more certain the person is that they are fine. The impairment and the inability to perceive the impairment arrive together.

Think about what this means in a professional context. The very confidence with which a sleep-deprived executive presents their analysis, makes their recommendation, or defends their decision is not evidence that their judgment is sound. It is a symptom of the problem.

What Six Hours of Sleep Per Night Does to Your Brain Over a Week

The acute impairment — a single long day, a single short night — is significant but recoverable. Chronic sleep restriction is something more insidious and, for most Hong Kong professionals, more relevant.

Restricting sleep to six hours or less per night across 14 consecutive nights results in cognitive impairment equivalent to up to two nights of total sleep deprivation. Crucially, unlike cognitive performance, the subjective experience of sleepiness stabilises — meaning people stop feeling as tired as they objectively are, while performance continues to decline.

After a week of six-hour nights, you feel approximately okay. Your brain is performing as if you haven't slept for 48 hours.

A Hong Kong University study found that 92% of the local working-age population was sleep deprived, with nearly 50% reporting these habits as long-term. Sixty percent were unaware they had a sleeping problem at all.

Sixty percent. Unaware.

The Specific Effects of Sleep Deprivation on Professional Performance

For professionals whose work depends on specific cognitive capacities, it is worth being precise about what sleep restriction actually impairs. Not reaction time in abstract tests — but the specific professional skills that matter most.

Sleep Deprivation and Decision-Making Under Uncertainty

Sleep deprivation particularly affects the prefrontal cortex regions responsible for executive decision-making, leading to impulsive choices, overconfidence in risky situations, and failure to adequately weigh potential negative outcomes.

For anyone in finance, law, investment, or any domain where risk calibration is a core professional skill, this is a direct hit to the primary tool.

How Poor Sleep Affects Your Ability to Read People

Research published in the journal Sleep found that sleep deprivation selectively impairs the accurate recognition of human facial emotions, particularly those most relevant to threat and reward detection.

On a week of inadequate sleep, you are less able to accurately read whether a client is genuinely engaged or quietly disengaging. Whether a direct report is struggling or coping. Whether the atmosphere in a negotiation has shifted. The social intelligence that experienced professionals develop over decades degrades measurably with each night of insufficient sleep.

You are not just slower and more tired. You are reading people less accurately — in meetings where that accuracy has significant professional consequences.

Sleep Loss and Learning From Mistakes

Sleep-deprived people fail to adequately learn from negative feedback. In fast-moving professional environments where iterating on poor decisions matters as much as making good ones, this is a compounding liability.

The Impact of Sleep Deprivation on Ethical Reasoning

Sleep deprivation impairs the deliberative reasoning processes that underlie ethical judgment, making impulsive, self-serving decisions more likely under conditions that would normally produce more considered responses. For anyone in a fiduciary or advisory role, this matters.

The Double Standard Built Into Hong Kong's Professional Culture

There is a cultural assumption embedded in Hong Kong's professional environment that the capacity for sustained output is a virtue in itself — that the person who pushes through, who manages on less sleep, who treats rest as optional, is demonstrating something admirable.

This assumption is not supported by the evidence.

We routinely accept sleep deprivation in professional environments in ways we would never accept intoxication — despite the fact that the research demonstrates equivalent impairment to cognitive function, judgment, and motor control.

No firm would run a trading desk staffed with mildly intoxicated professionals and consider that acceptable. Many are, functionally, doing something close to that — and calling it dedication.

The Performance Risk Nobody Is Measuring

We measure almost everything that matters in professional life. Performance. Revenue. Billable hours. Client satisfaction. Risk exposure. Compliance.

But the cognitive state of the people making all of those decisions — the actual functioning of the instrument being applied to every one of those problems — goes entirely unmeasured. There is no baseline cognitive assessment taken on adequate sleep, against which performance on five hours can be compared. There is no fatigue audit alongside the financial audit.

Fatigue is not just a wellbeing concern. It is a performance and risk management issue with real implications for the quality of decisions being made at every level of professional life.

What Sleep Actually Is as a Professional Asset

The standard framing of sleep — as self-care, as recovery, as a personal health matter — undersells what it actually is.

Sleep is not what you do instead of being productive. Sleep is the process by which the cognitive instrument you use for everything else is restored to operating condition.

The prefrontal cortex — the seat of judgment, planning, risk assessment, and ethical reasoning — does not run on willpower. It runs on adequate sleep. The emotional regulation that makes someone an effective leader under pressure comes from a nervous system that has had sufficient rest to maintain its window of tolerance. The creative, lateral thinking that produces good solutions to novel problems is a function of REM sleep, which is the first stage lost when nights are short.

The most useful reframe: getting adequate sleep is not what you do when you have time. It is what you do to ensure that the time you have is actually productive — that the decisions you make are the ones you would make at your best, not the ones you make at the equivalent of your third drink.

Frequently Asked Questions About Sleep Deprivation and Performance

How does sleep deprivation affect work performance in Hong Kong?

Hong Kong professionals average just 6.5 hours of sleep per night — below recommended levels — and 92% of the working-age population is classified as sleep deprived. The effects on work performance include reduced decision quality, impaired emotional recognition, overconfidence in risky situations, and difficulty learning from mistakes. These are not abstract effects. They show up in meetings, negotiations, and client interactions every day.

Is six hours of sleep enough for high-performing executives?

No. The research is clear that six hours per night produces cumulative cognitive deficits that do not plateau — meaning there is no stable equilibrium at six hours, only a continuing downward trajectory. By day 14 of six-hour nights, performance declines to levels comparable to 48 hours without sleep, while subjective alertness remains relatively stable.

What is the equivalent of sleep deprivation in terms of alcohol?

After 17 to 19 hours of continuous wakefulness, cognitive performance declines to levels equivalent to a blood alcohol concentration of 0.05% — the legal drink-drive limit in Hong Kong. After 24 hours awake, that rises to 0.10%, exceeding the legal limit everywhere in the world.

Can you catch up on lost sleep at the weekend?

Partially, but not completely. Studies show that even after several nights of recovery sleep, certain cognitive functions — particularly sustained attention and working memory — remain below baseline. The impairment accrues in ways that weekend sleep does not fully reverse.

How much sleep do executives actually need?

Most adults, including high-performing executives, require between 7 and 9 hours of sleep per night for full cognitive restoration. The proportion of people who genuinely function optimally on less than 7 hours is estimated at less than 3% of the population.

What are the signs that sleep deprivation is affecting my professional performance?

The challenge is that sleep deprivation impairs self-assessment — so the people most affected are often the least aware of it. External signs include increased irritability, overconfident decision-making, difficulty reading social cues, slower recovery from mistakes, and creeping cynicism about work that previously felt meaningful. If colleagues or family members have noted changes in your mood or judgment, this is worth taking seriously.

Where can I find a psychologist in Hong Kong who specialises in sleep and performance?

John Corbett is a psychologist based in Hong Kong working with executives, entrepreneurs, and senior professionals on performance, psychological wellbeing, and sleep-related issues. Consultations can be arranged via johncorbett.com.

A Note on What Actually Helps

The single most evidence-supported intervention for chronic sleep restriction is protecting sleep duration consistently — not attempting to recover it at the weekend.

For people in environments where sleep is genuinely constrained, the most practical step is knowing which hours represent peak cognitive performance — for most people, mid-morning after adequate sleep — and protecting those hours for decisions that require the most accurate judgment.

Scheduling your highest-stakes decisions for 10am on a Monday after a weekend of adequate sleep is not a small optimisation. Given the research, it may be among the most consequential professional habits available.

If your sleep has been consistently poor and these adjustments haven't moved the dial, that gap is worth exploring with a professional who understands both the psychology and the physiology of sleep.

John Corbett is a psychologist based in Hong Kong working with executives, entrepreneurs, and senior professionals on performance, psychological wellbeing, and recovery. To arrange a consultation, visit johncorbett.com