In 2022, Casper and Gallup entered into a new partnership to examine sleep and the role it plays in wellbeing, culminating in the Casper-Gallup State of Sleep in America 2022 Report. Among other key discoveries, poor sleep was linked to $44 Billion in Lost Productivity due to unplanned absenteeism from work.
More recent research has shown that poor sleep temperature is strongly linked to both depression and anxiety as well as to poor daily energy, with sleeping too hot more closely related to these conditions than sleeping too cold.
In Year 2 of the partnership, we have expanded the scope of our research to include the important role that proper temperature regulation plays in sleep and wellbeing outcomes. What’s more common: hot sleep or cold sleep? Who suffers more from these conditions? Is each similarly harmful to sleep quality and wellbeing outcomes, or is one more damaging than the other?
To answer these questions and more, Gallup surveyed the opinions of 3,979 randomly selected adults nationwide from the Gallup Panel.
So what’s more common, sleeping too hot or sleeping too cold? Among all American adults, 57% report sleeping too hot at least occasionally compared to 36% who report sleeping too cold. The negative effect on sleep quality for both conditions is substantial, but sleeping too hot is more harmful.
|Too Hot||Too Cold|
|Always/Most of the time||14%||6%|
|Rarely or Never||43%||64%|
When asked about the last time they slept too hot, 80% of respondents reported that their sleep improved compared to 1% who indicated that it worsened, a net negative of -79%. While cold sleep was detrimental as well, 9% of respondents reported that their sleep actually improved compared to 58% who said worsened, a net negative of -49%.
The biggest reason for why hot sleeping is worse for overall sleep quality than cold? Those who slept too hot “woke up a lot” 49% of the time compared to 32% of those who slept too cold.
|Too Hot||Too Cold|
And waking up frequently means only one thing: fewer hours of actual sleep. Those who typically sleep both too hot and too cold at different times throughout the night are the most sleep deprived. Three out of 10 (29%) of all-night comfortable sleepers get fewer than six hours of sleep each night compared to 46% of those whose temperatures swing back and forth.
|Comfortable throughout||Too hot||Too cold||Both at different times|
|Under 6 hours||29%||39%||44%||46%|
|7 to 9 hours||40%||31%||28%||25%|
Those who are both too hot and too cold during the same night are 59% more likely to get fewer than six hours of sleep than are those who sleep comfortably throughout the night.
Poor Sleep Temperature Closely Linked to Next Day Experiences
But what happens when we get up for the day? How are our daily emotional experiences influenced by poorly regulated sleeping temperature? Those who typically run either too hot or too cold at night are both considerably more likely to experience unwanted outcomes in their daily lives. For example, only 24% of those who rarely or never sleep too hot report having experienced irritability the day before. But this balloons to 45% daily irritability among those who typically sleep too hot.
“Did you experience this feeling a lot of the day yesterday?“
|Always or most of the time too hot||Rarely or never too hot||Always or most of the time too cold||Rarely or never too cold|
People who typically sleep too hot are 44% more likely to experience low energy on a daily basis than those who rarely or never sleep too hot.
To better understand what behaviors are most closely related to good – or poor – sleep quality, we analyzed several different aspects of personal health choices. While regular exercise has little relationship to sleep temperature, eating healthy all day does. Two-fifths (41%) of adults who sleep comfortably throughout the night ate healthy the entire day prior compared to just 30% of those who were too hot and too cold intermittently throughout the night.
People who sleep comfortably throughout the night are 37% more likely to have eaten healthy throughout the prior day than were those who were both too hot and too cold at different times the same night.
Smoking is also linked to poor sleep temperature. Those who typically run either too hot or too cold than are both statistically more likely to be smokers.
Those basics duly noted, it’s not just simple habits such as eating right or smoking. Bedtime routines also matter to sleep temperature regulation. Eating, consuming caffeine, and screen time within one hour of bedtime are all associated with typically sleeping too hot or too cold.
For example, when compared to those who rarely or never sleep too hot, adults who typically sleep too hot are 62% more likely to eat within one hour of bedtime. And compared to those who rarely or never sleep too cold, those who typically sleep too cold are more than twice as likely to be bedtime eaters.
|Always or most of the time too hot||Occasionally too hot||Rarely or never too hot||Always or most of the time too cold||Occasionally too cold||Rarely or never too cold|
|Food within one hour of bedtime (% Always or most of the time)||21%||16%||13%||30%||16%||14%|
|Caffeine within one hour of bedtime (% Always or most of the time)||18%||13%||13%||19%||13%||13%|
|Caffeine within one hour of bedtime (% Always or most of the time)||83%||78%||72%||80%||78%||75%|
Typically hot sleepers are 38% more likely to commonly consume caffeine before bed compared to those who rarely or never sleep too hot. Typically cold sleepers are 46% more likely.
So where in the U.S. are the hottest sleepers, anyway? Americans living along the east coast are the most likely to report regularly sleeping too hot than those in other parts of the country. The residents in the band of states starting with New York in the Middle Atlantic region directly south down to Florida in the South Atlantic region report sleeping hot always or most of the time slightly more likely than those out west. East South Central and the East North Central sleepers come in a close second.
The importance of high quality sleep to wellbeing has long been understood. Sleep serves a larger purpose than leaving us feeling well rested. Research has shown that our capacity for learning grows while we are sleeping as each night of sleep allows us to process what we learned the prior day, thus serving a critical purpose in how we live and work.
The role of sleep temperature in influencing sleep quality, in turn, is profound. Sleeping too hot or too cold are both detrimental to sleep quality and duration, but sleeping too hot is considerably more common and usually more harmful. As such, reducing hot sleeping would likely result in a better return on investment when addressing the issue of temperature regulation during sleep.
Fortunately, for those who are prone to sleeping too hot or too cold there are practical things that people can do to maximize their chances of a well-regulated temperature during sleep (or while trying to sleep). This includes not smoking and eating healthy throughout the day, but also critically extends to bedtime habits such as food, caffeine, and screen time consumption.
Results are based on a survey conducted by web from Feb. 10 through Feb. 17, 2023, with 3,962 adults, ages 18 and older, living in all 50 U.S. states and the District of Columbia as a part of the Gallup Panel. For results based on this sample of national adults, the margin of sampling error at the 95% confidence level is ±1.9 percentage points for response percentages around 50% and is ±1.2 percentage points for response percentages around 10% or 90% (design effect included). For subgroups, the margin of error will be larger, typically running from around ±4 to 5 percentage points for response percentages near 50% and ±2 to 3 percentage points for response percentages around 10% or 90%.
Gallup uses probability-based, random sampling methods to recruit its Panel members. Currently, there are about 100,000 Gallup Panelists nationwide.
Gallup weighted the obtained samples to correct for nonresponse. Nonresponse adjustments were made by adjusting the sample to match the national demographics of gender, age, race, Hispanic ethnicity, education and region. Demographic weighting targets were based on the most recent Current Population Survey figures for the aged 18 and older U.S. population.
Learn more about Gallup Panel.