How long does it take you to fall asleep at night? I used to pride myself on being able to fall asleep in a heartbeat. In fact, I used to snap my fingers and say, “I can fall asleep on a dime!” Only recently did I realise that what I was really saying was, “Hey, I’m sleep deprived!” Let me explain…
As a society, we are shortchanging ourselves on sleep by about 60 – 90 minutes a night. If you wonder whether you’re getting enough, here are some criteria to help you decide:
- Do you need an alarm clock to wake you up in the morning? Or, two alarm clocks—one close enough to hit the snooze button and one across the room to make you get out of bed?
- Do you wake up feeling refreshed or tired?
- How is your daytime energy? Do you run out of steam by late afternoon?
- How much sleep do you get when you don’t have to wake up [on weekends or when you’re on vacation]?
- How quickly do you fall asleep at night? This is the criterion used by sleep researchers and it’s called the ‘sleep latency period.’ For normal, well-rested people, this transition period takes fifteen to twenty minutes. If you fall asleep in less than five minutes—or even 10—you are, by definition, sleep deprived.
When patients complain about fatigue, I always begin by asking two questions:
- How much sleep are you getting at night? The answer is often ‘six to seven hours.’
- How much sleep do you need to function at your best? [Not how much you can get away with, but how much you really need to be at the top of your game.] The answer is usually ‘eight.’
Even a medical student could make the diagnosis: not enough sleep!
How much sleep do we need? Most adults need eight to nine hours a night, which is what people were getting until 1913, when Thomas Edison perfected the tungsten filament incandescent light bulb—artificial light. Today we average about seven hours a night, even though we haven’t changed physiologically since Edison’s time. We’re cheating ourselves of sleep in order to work, watch TV or socialise. It hasn’t been a very good tradeoff.
What’s the cost of sleep deprivation?
The damage is much greater than we realise. We fall asleep while driving. We become more prone to infection because our immune system is stimulated during sleep. We make mistakes on the job, causing injury or financial loss. Our concentration and short-term memory are impaired, and intellectual function is diminished.
In a 1999 Toronto Star article on sleep, Dr. Stanley Coren, a psychologist at the University of British Columbia in Vancouver, said, “One hour’s lost sleep out of eight results in a drop of one point of IQ and for every additional hour lost, you drop two points. And it accumulates. So if you cheat on sleep by two hours a night over a five-day week, you’ve lost 15 points.” Also, significantly, sleep deprivation affects our mood. We become irritable and depressed.
Note that many of the symptoms of sleep deprivation are also symptoms of stress. But, in addition, tired people are less resilient when handling stressful situations. So lack of sleep is a double whammy. Going to work without proper rest is like starting your day with one foot in a hole.
Expert advice
- Assess your sleep situation. How much sleep are you getting now?
- How much do you need to function at your best? How do you fare with the five sleep criteria?
- Go to bed a half hour earlier for the next few nights and see what happens.
- Then add another half hour for a few nights.
- Continue adding to your sleep until you can wake up naturally, feeling refreshed.
- Sleep in for an hour or two on weekends if you get behind the week.
Sleep debt
The difference between the amount of sleep we need and the amount of sleep we get is called ‘sleep debt.’ If you need eight hours a night but only get seven, you have a sleep debt of one hour. As Dr. Coren points out in his wonderful book Sleep Thieves, if this continues for a week, you then have an accumulated sleep debt of seven hours. The effect is much like losing all seven hours in the same night. The good news is that you can repay the sleep debt. So if you fall behind, a few consecutive nights of full, uninterrupted sleep will usually return you to full function.
Five years ago I stopped setting my alarm and simply woke up when my body was ready. Of course, I had to go to bed early enough to wake up naturally and still be on time for work. But the result has been dramatic. I feel profoundly better every day for doing this. And so do my patients who have started getting the sleep they need.
A good night’s sleep is the best way to start your day-don’t leave home without it!
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