Is 6 Hours of Sleep Enough? The Six-Hour Trap for Executives

For most adults, no. In a 2003 lab study, two weeks of six hours or less in bed produced thinking deficits comparable to up to two nights of no sleep at all, and the people in it were largely unaware of how impaired they had become. That second finding is the trap. Six hours feels like enough because the part of you that would notice is the part that is running short.

Key takeaways

Key takeaways

1. In a 2003 lab study of 48 adults, six hours or less a night for 14 days produced deficits comparable to up to two nights without sleep.
2. People in that study were largely unaware they were impaired, so "I feel fine" is not evidence.
3. In Belenky's study, about 6.3 hours of actual sleep slowed reaction speed, and three recovery nights did not fully fix it.
4. After 17 to 19 hours awake, some test results matched or were worse than a 0.05% blood alcohol level.
5. Canadian and US guidelines call for seven or more hours a night, with consistent bed and wake-up times.
6. Track seven nights before you change anything, then fix your wake time and use 10 reading minutes and 5 still minutes as your runway to bed.

This is coaching information, not medical advice. If you think you have a sleep disorder, talk to your doctor. If you want a quick read on where you stand first, take the sleep quiz.

Is 6 hours of sleep enough?

The expert consensus says no. In 2015 a panel of 15 sleep experts convened by the American Academy of Sleep Medicine and the Sleep Research Society recommended that adults aged 18 to 60 sleep seven or more hours a night on a regular basis. They linked regularly sleeping less than seven hours to weight gain, diabetes, high blood pressure, heart disease, stroke, depression and higher risk of death, plus impaired performance, more errors and more accidents.

Canada's 24-Hour Movement Guidelines for adults 18 to 64, from the Canadian Society for Exercise Physiology, land in the same place: seven to nine hours of good-quality sleep on a regular basis, with consistent bed and wake-up times. Note the second half of that sentence. Timing is part of the guideline, and it is the part most executives skip.

Plenty of Canadians fall short. Statistics Canada analysed nearly 11,000 respondents to the Canadian Health Measures Survey (2007 to 2013). Adults 18 to 64 averaged 7.12 hours a night, but about one in three slept less than seven. Only 55% said their sleep was refreshing most or all of the time, and 33% reported trouble staying awake during normal waking hours at least sometimes. The data is self-reported and over a decade old, so read it as a rough guide.

What did the research actually find?

Van Dongen 2003: fourteen nights of restricted sleep

Hans Van Dongen and colleagues put 48 healthy adults aged 21 to 38 in the lab. Some got 4, 6 or 8 hours in bed a night for 14 days. Others went three nights with no sleep at all. Restricting sleep to 4 or 6 hours caused cumulative, dose-dependent deficits on every cognitive task they tested. By the end, six hours or less a night had produced deficits equivalent to up to two nights of total sleep deprivation.

Lapses in alertness rose almost in a straight line once time awake went past about 15.84 hours a day. Every extra hour beyond that adds to the debt, night after night.

Belenky 2003: the dose-response study

Gregory Belenky and colleagues ran 66 volunteers, all holding commercial driver's licences, through seven nights of 3, 5, 7 or 9 hours in bed, then three recovery nights of 8 hours. The group given 7 hours in bed actually slept about 6.3 hours a night, which looks a lot like a typical executive's week.

That group's reaction speed dropped and then levelled off at a lower plateau, without more outright lapses. After three full recovery nights, the 7-hour and 5-hour groups still had not returned to baseline. The authors concluded the brain adapts to chronic restriction by stabilising performance at a reduced level. You get used to running slower, then you call it normal.

Williamson and Feyer 2000: hours awake versus alcohol

Ann Williamson and Anne-Marie Feyer tested 39 people (30 transport industry workers and 9 army personnel) across 28 hours without sleep and again after measured doses of alcohol. After 17 to 19 hours awake, performance on some tests was equal to or worse than at a blood alcohol concentration of 0.05%. With longer time awake, some results reached the level of 0.1%, and response speed on some tests was up to 50% slower.

If you are up at 5:30 a.m. and still answering email at 11 p.m., you have been awake for 17.5 hours. You would not take a board call tipsy. Plenty of leaders take them at hour 17 every week.

What the research does not prove

The samples are small: 48, 66 and 39 people. They are well-controlled lab studies, which is why they are trusted, but they are not population surveys.

Most participants were young. Van Dongen's group was 21 to 38. That cuts both ways for a 45-year-old executive: you may handle short sleep worse, or you may have adapted habits that partly cover for it. The studies do not tell you which.

Lab tasks are narrow. A reaction-time test is only a proxy for how you will handle a negotiation or a hiring decision.

Individual need varies, and these are group averages. The consensus panel still set the floor at seven hours, so assume you are not the exception until your audit says otherwise.

The health links to short sleep in large surveys (heart disease, diabetes, mortality) are mostly associations. People who sleep less also differ in stress, work and health, so those numbers do not prove short sleep causes disease on its own.

Why can't you feel your own sleep debt?

In Van Dongen's study, sleepiness ratings jumped in the first few days of restriction and then barely moved, while measured performance kept getting worse. Self-rated sleepiness did not even reliably tell the six-hour group from the four-hour group. The authors described participants as largely unaware of their growing deficits.

Belenky's data fits the same pattern. Performance stabilised at a lower level, and stable feels normal. Your reference point drifts down with you. So "I feel fine on six" is not evidence. The only fair test is to measure.

What does short sleep do to judgment, mood and risk-taking?

Mood suffers. In Dinges and colleagues' 1997 study, 16 young adults limited to about five hours a night for a week reported steadily rising fatigue, confusion and tension, with falling vigour.

Self-control drops and hostility rises. Christian and Ellis (Academy of Management Journal, 2011) studied nurses at a large medical centre and students in a lab. In both samples, sleep deprivation lowered self-control and increased hostility, which in turn predicted more deviant behaviour at work.

Leaders' bad nights spread to their teams. Barnes, Lucianetti, Bhave and Christian (Academy of Management Journal, 2015) tracked leaders and their staff across ten workdays. On days after poor-quality sleep, leaders were more depleted and more likely to behave abusively, and their units were less engaged that day. The effect ran through sleep quality rather than hours, so a long night of broken sleep does not get you off the hook. There is more on this in sleep and leadership.

Risk tolerance shifts. Killgore and colleagues (Journal of Sleep Research, 2006) gave 34 healthy adults a gambling task rested and again after about 49 hours awake. After sleep loss they chose the risky decks more often as the game went on, and older participants chose more riskily than younger ones. That was extreme deprivation, so do not stretch it to one short night. It does show which way judgment moves when the tank runs dry.

Short sleep also sits on the list of founder burnout signs I would watch for.

What does sleep deprivation cost a business?

The best-known national estimate is RAND Europe's 2016 cross-country analysis of five countries, including Canada. Using UK workplace survey data from over 62,000 people plus other national data, it modelled what insufficient sleep costs in lost productivity and higher mortality.

For Canada, RAND estimated about 78,000 working days lost each year to insufficient sleep. If every short sleeper moved into the seven-to-nine-hour range, it modelled a gain of up to US$21.4 billion a year in 2015 prices, about 1.35% of GDP. RAND's own summary gives a slightly different range for Canada (0.85% to 1.56% of GDP). Treat both as model estimates with wide error bars.

Inside one company the cost never shows up as a line item. It shows up as a bad hire you would have caught rested, or a deal you priced too low because you wanted the meeting over. No study above measures that, which is why I would treat sleep as an operating issue for a leadership team. More on that in the executive health hub.

Run a seven-night sleep audit

You cannot feel this one, so measure it. Track seven consecutive nights, including a weekend, in a notebook or your phone. A wearable helps, but the log matters more.

Each morning, write down:

1. Time you got into bed and time the lights went out.
2. Your best guess at when you fell asleep.
3. Time you woke and whether an alarm woke you.
4. Number of times you woke in the night.
5. Caffeine after noon (yes or no) and alcoholic drinks the evening before.
6. Time you last looked at a work screen.
7. A 1 to 5 rating of how alert you felt at 10 a.m. and again at 3 p.m.
8. Anything a partner noticed: loud snoring, or pauses in your breathing.

At the end of the week, work out three numbers. Average hours asleep: under seven answers the headline question. The gap between weekday and weekend wake times: I would read more than an hour as paying back debt on the weekend. Mornings woken by an alarm: if it is all seven, you probably never reach the end of your natural sleep. Then check whether late screens, alcohol and afternoon caffeine line up with your lowest 3 p.m. scores.

A 2% Solution plan for better sleep

The 2% Solution is the framework I have taught since 2015: 30 minutes a day, which is about 2% of your 24 hours. Fifteen minutes moving, five minutes still, ten minutes reading. It maps neatly onto sleep, because busy people usually lack a runway into bed. Here is how I would set it up starting this week.

Fix your wake time first. Pick one wake time you can keep seven days a week, including Saturday. It anchors everything else, and it is easier to control than a bedtime.

Count back for bedtime. Take your wake time, subtract seven and a half hours of sleep plus the time it usually takes you to fall asleep, and that is lights out. If you wake at 5:45, lights out is about 10 p.m.

Use the 10 reading minutes at night. Make them the last thing you do, in bed or near it, with paper. Fiction, or anything unrelated to work. Its real job is to replace the scroll and the inbox check.

Use the 5 still minutes as the bridge. Before you read, sit or lie down for five minutes without a screen. Breathe slowly. If work is still circling, write it on a card for the morning and leave it there.

Use the 15 moving minutes earlier in the day. A brisk walk outside in the morning or at lunch is enough to start. Keep hard training away from the last hour or two before bed if you notice it keeps you wired.

Set two cut-offs. A last work screen at least an hour before lights out, and caffeine finished by early afternoon. Let your log tell you whether alcohol is costing you.

Repeat the audit after four weeks. If your average is still under seven hours, look hard at your calendar, because more willpower will not fix a schedule problem.

When should you see a doctor about sleep apnea?

Seven hours in bed does not help much if your breathing keeps interrupting your sleep. In Canadian data, sleep apnea is more common in men and becomes more common with age.

Statistics Canada's 2016 to 2017 health measures data found 6.4% of Canadians aged 18 to 79 reported a sleep apnea diagnosis. Using a standard screening questionnaire (STOP-BANG), 14.9% were at high risk, including 24.6% of men and about one in five adults aged 40 to 79.

STOP-BANG checks for loud snoring, daytime tiredness, observed pauses in breathing, high blood pressure, a BMI over 35, age over 50, a large neck circumference and male sex. If several of those apply to you, or a partner has seen you stop breathing, book an appointment with your family doctor and ask about a sleep assessment. The same goes if you nod off while driving, or get seven hours and still wake up exhausted. That needs a doctor before it needs a coach.

Where to start this week

Run the seven-night audit, pick your wake time, and put the 10 reading minutes at the end of your day. If you want help turning what the audit shows into a schedule that works for your role, book a free 20-minute call and bring your numbers.