1 August 2009

Food for Thought

Not sleeping enough and not sleeping well is not OK
‘Most of us don’t get enough sleep and this promotes weight gain and increases our risk of developing diabetes and heart disease,’ says dietitian and exercise physiologist Caitlin Reid in her new book, Health & the City. ‘Inadequate sleep also increases daytime sleepiness and our susceptibility to injury along with compromising decision making and concentration,’ she says. Chronic lack of sleep affects our health, our work and our safety. So next time a colleague boasts that they ‘get by on four or five hours sleep a night,’ don’t envy them. Pity them. And maybe suggest they get help.

US researchers analysing data of 18,000 adults in the National Health and Nutrition Examination Survey found a correlation between BMI and hours of sleep. Those who got less than four hours of sleep a night, were 73% more likely to be obese than those who slept seven to nine hours. In a separate study of 924 adults, researchers determined that two hours less sleep per week amounted to an increase in BMI of 10. They’re still at a loss to explain how sleep helps our weight, but there are lots of theories. It may be related to lower production of the hormone leptin (a natural appetite suppressant) with sleep deprivation. In the meantime, it’s a good reason to make sure you get enough shut-eye.


Chronic sleep deprivation has been linked to high blood pressure, heart disease and diabetes. Short sleepers (i.e. people getting less than six hours sleep a night), are prone to abnormal blood glucose levels, possibly putting them at risk for diabetes, says Lisa Rafalson of the University at Buffalo in New York, at the Conference on Cardiovascular Disease Epidemiology and Prevention in Florida in March 2009. Using data from a large six-year study, Rafalson and colleagues identified 91 people whose blood glucose rose during the study period and compared them to 273 people whose glucose levels remained in the normal range. They found the short sleepers were far more likely to develop impaired fasting glucose than those who slept six to eight hours.

Broken sleep is a problem too. Dr Katherine Stamatakis and Dr Naresh Punjabi carried out a small experimental study (published in June 2009 in Chest) with eleven healthy adults who volunteered for two nights of broken sleep. They found that fragmentation of sleep across all stages of sleep was associated with a decrease in insulin sensitivity and glucose effectiveness.

‘Most of us need between seven and eight hours sleep a night,’ says Caitlin, ‘but many of us aren’t getting enough. We toss and turn. We replay conversations. We think of tasks to do. Our phones beep and before we know it, dawn is breaking and the birds are singing.’

Caitlin’s top tips for getting enough shut-eye

  • Establish regular sleep patterns – go to bed in a dark, quiet and comfortable room and get up at the same time every day.
  • Turn off your cell phone.
  • Avoid caffeine, alcohol and nicotine immediately before bed.
  • Eat any large meals at least three hours before going to bed.
  • Exercise regularly at least three hours before bed – any later can make sleep difficult.
  • Try a snooze food an hour before bed like warm milk. Calcium helps the brain use the tryptophan to make the sleep-inducing substances serotonin and melatonin. Tryptophan is an amino acid found in milk, yoghurt, almonds, turkey and tuna.

PS If insomnia has become a chronic problem GI-guru Jennie Brand-Miller recommends a course in “mindfulness”.


Anonymous said...

I have a 1 month old baby girl and an extremely active 4 year old boy who believes sleep is a waste of time. I can already feel the effects of no sleep. I am cranky, forgetful, clumsy, and about to go back to work. Is there any hope for us busy sleepless moms???

Bryan Andrews said...

Thats a really interesting article. For a number of years through through a succession of busy jobs and evening exercises, I've take around 6 hours of sleep a night at most and some nights even less than that. I'd better go back and look at changing that.

It would be great to be able to read some of the background behind the US study to understand the difference in weight / BMI that good sleep patterns would bring and if I moderate my sleep patterns will it help me to loose some more weight and reduce BMI?

GI Group said...

Hi Bryan, the sleep/weight correlation is interesting. And aiming to get more sleep is probably a good thing. If you want to do some research, Google pubmed and topics like 'obesity and sleep'. Meanwhile, here's an interesting piece that may help. It makes the useful point that we all have different sleep needs and gives some tips on how to find what's right for you.

Calculating Sleep Needs

"Sleep needs vary greatly by individual, and there is no single good test to measure what an individual's sleep need is," Dr. Eliasson said.

On average, adults need regular episodes of about 8 hours 15 minutes per 24-hour period -- but that's a statistical average. The range is much broader: 4 hours to 10 hours, depending on the individual. Children require about 9 hours, and teens may need a little more. By adulthood, adults generally need about 8 hours per night, according to Dr. Eliasson.

Contrary to common belief, aging in itself doesn't reduce the amount of sleep required, he noted. Other things may conspire to interfere with a regular schedule of night-time sleeping though, such as medical conditions, orthopedic issues, medications, mental health and living circumstances -- whether one has to get up at the same time each morning to go to work or is retired, for example.

The result is that older people often break up their sleep into shorter episodes at night combined with daytime napping.

If you want to pinpoint the ideal amount of sleep for you, Dr. Eliasson suggests a six-month experiment: Attempt to get very regular amounts of a certain length of sleep for a few weeks, and keep a diary recording how you feel during that period. For example, get 7 hours of sleep per night for three to four weeks, noting what time you go to bed and get up, when you nap, and how you feel. Keep those regular sleep hours on week days, weekends and holidays. Then, expand your sleep time to 7 hours 20 minutes per night for three to four weeks recording similar variables. Then, expand to 7 hours 40 minutes per night for three to four weeks, and so on. Over six months, you will be able to zero in on the amount of sleep needed to feel rested and be functioning in peak form.

"This sort of experiment takes a lot of dedication and time, and not many people are willing or able to make this happen," Dr. Eliasson observed.