35% of Americans report getting less than 7 hours of sleep during a typical 24-hour period, 48% report snoring, 38% report unintentionally falling asleep during the day at least once in the preceding month, and 5% report nodding off or falling asleep while driving at least once in the preceding month.1 While people have been sleeping less over time, the incidence in obesity has been increasing and physical inactivity has been decreasing simultaneously.2
The researchers for this study investigated whether acute partial sleep deprivation had an effect on appetite and food energy intake and concomitantly on physical activity.3 The study results indicated that a single night of reduced sleep subsequently increased food intake, and to a lesser degree the night of reduced sleep was associated with men’s estimated physical activity–related energy expenditure. The results raise the possibility that sleep restriction may be a factor that promotes obesity, which will need to be verified in larger studies.
The study population was 12 normal-weight men, aged 18 to 29, who were students recruited by local advertisements. Individuals were eligible for the study if they were generally healthy, didn’t use medications, typically slept about 7 hours 30 minutes to 8 hours nightly, had normal body weight (20 < body mass index <25), had a stable body weight during the preceding 6 months, and moderate physical activity. Smokers were accepted if they smoked fewer than 5 cigarettes each day. Volunteers were excluded from the study if they worked at night, used psychostimulant and/or narcotics, took sleeping pills, had an eating disorder, and drank more than 3 cups caffeine daily or more than 10 grams of alcohol per week. They were also excluded if they were dieting or fasting, snacked on foods more than twice daily, and did not like the foods offered as part of the study. None of the participants were informed about the goals of the experiment, the meal structure, the measurements performed, the duration of sleep, or the activities proposed.
Over two consecutive days immediately prior to the study session, the participants were asked to record in a diary their bedtime, time of waking, and quality of sleep. They were also supposed to record their physical activities and weigh, using a scale they were given, and record all of their ingested foods. This was done to ensure participants were following the lifestyle chosen for study inclusion.
In each study session, three participants were tested simultaneously. During the first night of each 48-hour study session, the participants had either approximately 8 hours (from midnight to 8:00am, classified as normal sleep session) or approximately 4 hours (from 2:00 to 6:00am, classified as sleep restricted session) of sleep. All the foods they consumed subsequently (jam on buttered toast for breakfast, buffet for lunch, and a free menu for dinner) were eaten freely. Their physical activity was recorded by an actimeter attached at their waist. Feelings of hunger, perceived pleasantness of the foods, desire to eat some foods, and sensations of sleepiness were also evaluated.
During the first night, sleep duration was shorter for the SRS participants than the NSS participants. The actimeters they wore measured the time spent in sleep during the SRS at 3 hours and 46 ± 14 minutes and NSS at 7 hours 14 ± 40 minutes. The participants’ own estimations were 3 hours 44 ± 11 minutes for the SRS group and 7 hours 14 ± 36 minutes for the NSS group. The SRS participants found the duration of their sleep insufficient in comparison with the NSS participants, but quality of sleep was judged satisfactory in both SRS and NSS groups. The shorter sleep duration in the SRS induced a stronger sensation of sleepiness, but both SRS and NSS participants reported a similar motivation to engage in physical activity during the morning.
During the first day of the study session, both Sleep Restricted Session (SRS) participants and Normal Sleep Session (NSS) participants had similar energy and macronutrient (fat, protein, and carbohydrate) intake.3 During the second day, there was no significant difference for hunger sensation during the entire day between the two sessions, but hunger before breakfast was greater in the SRS participants than in the NSS participants. Similarly, hunger was greater before dinner in the SRS participants than in the NSS participants. Total energy intake was 22% higher in the SRS participants than in the NSS participants. There was not an increase in energy intake during lunch or the afternoon, but an increase in energy intake was observed during breakfast (45%) and dinner (56%). The proportion of carbohydrate, protein, and fat intake did not differ between the SRS participants and NSS participants at breakfast, because breakfast was a fixed entity of pre-made jam on buttered toast. At lunch, 35% less chicken and 20% more bread were ingested in the SRS participants than in the NSS participants. During the dinner, 98% more lipids were eaten by the SRS participants than the NSS participants.
- Centers for Disease Control and Prevention. CDC Features: Insufficient Sleep is a Public Health Problem. http://www.cdc.gov/Features/dsSleep/index.html. Accessed September 1, 2016.
- Centers for Disease Control and Prevention. Adult Obesity Facts. http://www.cdc.gov/obesity/data/adult.html. Accessed September 1, 2016.
- Brondel L, Romer MA, Nougues PM, Touyarou P, and Davenne D. Acute partial sleep deprivation increases food intake in healthy men. American Journal of Clinical Nutrition. 2010; 91(6):1550-1559.