When young men slept less, they burned a little more energy during the night because they were awake longer—but this extra burn didn’t add up to more total energy burned over the whole day.

Scientific Claim

Three nights of shortened sleep (3.5 hours per night) in healthy young men caused a significant increase in nighttime energy expenditure (by 55 kcal, p<0.001) during the sleep restriction night, likely due to prolonged wakefulness, but this was offset by no change in total daily energy expenditure.

Original Statement

“Night-time EE on day 3 (00:00 to 07:00) was higher in the 3.5-h sleep condition than in the 7-h sleep condition (7-h sleep, 409 ± 37 kcal/d; 3.5-h sleep, 464 ± 45 kcal/d, p < 0.001). The 48-h total energy expenditure (TEE) did not differ significantly between the 7-h and 3.5-h sleep conditions.”

From study:Effect of shortened sleep on energy expenditure, core body temperature, and appetite: a human randomised crossover trial

Evidence Quality Assessment

Claim Status

appropriately stated

Study Design Support

Design supports claim

Appropriate Language Strength

definitive

Can make definitive causal claims

Assessment Explanation

The continuous calorimetry and statistical analysis of hourly data support definitive causal language. The distinction between nighttime spike and total EE is clearly documented and justified.

Evidence from Studies

Supporting (0)

No supporting evidence found

Contradicting (1)

Effect of shortened sleep on energy expenditure, core body temperature, and appetite: a human randomised crossover trial

Randomized Controlled Trial

Human

2017 Jan 10

The study found that sleeping less didn’t make people burn more calories overall or even at night — it just made them hungrier, which could lead to eating more and gaining weight.

Source Study

Effect of shortened sleep on energy expenditure, core body temperature, and appetite: a human randomised crossover trial

Score: 46

DOI: 10.1038/srep39640

Similar Assertions

Even after sleeping only 3.5 hours a night for three nights, young men burned the same total amount of energy and used the same mix of carbs and fats as when they slept 7 hours.

90%

When young men slept less, their bodies released more of the stress-related chemical norepinephrine, especially at night and in the morning, which may be a sign their stress system was overactive.

77%

When young men slept less, their body’s internal temperature dropped slightly over two days, suggesting their body’s natural daily temperature cycle was disturbed.

74%

After sleeping only 3.5 hours a night for three nights, young men reported feeling much hungrier and more tempted to eat, and less full after meals, even when they ate the same food as when they slept longer.

72%