Article Index

The risks of limited sleep

Epidemiological risks of insufficient sleep

In explaining the epidemiological evidence, Dr. Solet showed a slide that had a color-coded map of the United States showing the age-adjusted percentage of adults who reported 30 days of insufficient sleep or rest. Massachusetts has room for improvement.

There are two groups that are at special risk of being under-slept: the under-resourced who may be living in conditions beyond their control and the over-committed and ambitious who may take on more than is possible.

These maps from The Centers for Disease Control and Prevention (CDC) showed an intersection in epidemics in the states of the under-slept with a high incidence of diabetes and obesity. In discussing obesity, insufficient sleep causes the appetite to increase and the satiation level to drop,leading to overeating. When you’ve been up all night, you will be hungrier.

The people who have insufficient sleep will have a sleep debt. Just like having a credit card debt, the balance has to be paid off, in this case with sleep.

Study citation: Jeffrey S. Flier and Joel K. Elmquist, PhD “A Good Night's Sleep: Future Antidote to the Obesity Epidemic?”, Ann Intern Med. [editorial] 141, no. 11 (2004): 885-886. doi:10.7326/0003-4819-141-11-200412070-00014.

Physiological consequences of sleep debt

Leptin is a hormone that signals satiation. With insufficient sleep, Leptin levels drop and levels of ghrelin, which regulates appetite, increase. Ghrelin signals the body to turn on the hunger and fat store. This signals a negative energy balance, which in turn can increase hunger and lead to obesity.

People think if they are up for a longer period of time, they will burn off the extra calories, but research has proven them wrong. When tired, many head for the refrigerator rather than for bed. They gain weight.

There is also the possibility of immune cell activation and increased inflammation as well as irregularities in stress hormone regulation.

Dr. Solet made her point regarding food marketing practices by explaining how the recent analysis of portion sizes in cookbooks over the years shows increases and in general, how the food industry has supersized portions. The proliferation of fast food restaurants has contributed to the problem of obesity and grab and go eating.

Research from the CDC (Obesity data from CDC; Sleep data from Roffwarg in Science, 1966, National Sleep Foundation polls, and from Hale, Lauren in the Journal of Public Health, 2005) showed the increase of obesity from 1960 to 2000, while at the same time the chart showed mean hours of sleep have been dropping between 1960 to 2000. In 1960 the average sleep duration was 8.5 hours.

While the current average may be 7 hours, Dr. Solet said some research seems to indicate we may need closer to 9 hours of sleep.

Another chart showing how much sleep pro athletes get indicates they sleep more than most people do. They are paid to be in their best form, which supplies extra incentive to get enough sleep. The chart makes the point that we need more sleep to maximize our own capacities.

Studies cited: 1)  Roffwarg H.P. et al, “Ontogenetic Development of the Human Sleep-Dream Cycle,” Science 152, no. 3722 (1966): 604-619.           2)  Lauren Hale, “Who has time to sleep?” Journal of Public Health 27, no. 2 (2005): 205–211. doi:10.1093/pubmed/fdi004.

Altered memory and cognition

Restricted sleep impairs vigilance. Lack of sleep causes poor choices, impacts memory and cognition.

In a study (Van Dogen, Sleep, 2003) where the participants were rated on their vigilance after 8, 6 and 4 hours of sleep and then self-reported on how they thought they were doing, the 6 and 4-hour sleep-participants showed they thought they were doing better than their actual performance. They had no insight into the fact that their vigilance was so impaired.

When people are repeatedly awakened during the night, Dr. Solet explained many will not remember any details because the memory is not fully online during sleep. She made the point that just because you are in bed for eight hours doesn’t mean you sleep for eight hours.

Along with arousals during the night, there is the sleep latency factor—the amount of time needed to fall asleep. Another good example of the sleep-deprived are the doctors who have been up and on call for more than 24 hours and then get into a car to drive home.

A study in which Dr. Solet was a co-author, “Sleep Disruption due to Hospital Noises: A Prospective Evaluation”, found study subjects unable to accurately report how many times they had been awakened by noise during the night. However, Dr. Solet informed us this particular finding of not remembering accurately was not delineated in the findings because it was expected.

Study citation: Buxton O.M. et al, “Sleep Disruption due to Hospital Noises: A Prospective Evaluation”, Ann Intern Med. 157, no. 3 (2012): 170-179. doi:10.7326/0003-4819-156-12-201208070-00472. Author information: Orfeu M. Buxton, PhD, Jeffrey M. Ellenbogen, MD, Wei Wang, PhD, Andy Carballeira, BM, Shawn O'Connor, BS, Dan Cooper, BS, Ankit J. Gordhandas, SB, Scott M. McKinney, BA, Jo M. Solet, PhD.

Review of effects of insufficient sleep

• Impaired attention and reaction time
• Decreased memory and concentration
• Worse mood, depression
• Impaired task completion
• Psychosocial difficulties
• (Higher) Risk of injuries and falls
• (Higher) Incidence of pain and inflammation
• Weight gain
• Diabetes
• Cardiovascular disease
• Increased consumption of healthcare resources