September 17, 2026, 6:03 pm | Read time: 4 minutes
It’s generally nice to sleep in the same bed as your partner. However, this doesn’t always have a positive effect on your health. A new study suggests that a partner’s poor sleep can also negatively impact your own diet.
In a long-term relationship, many people notice that their partner’s sleep habits affect their own sleep. From snoring to different sleeping and waking times, there are numerous factors that can influence your sleep. It’s not surprising that some couples prefer to sleep in separate beds to start the day refreshed. It’s known that poor and insufficient sleep negatively affects eating habits. However, the new insight is that sleep affects not only the diet of the poor sleeper but also that of the partner. This is suggested by a Canadian study conducted at Concordia University in Montreal.1
How Researchers Studied the Link Between Sleep and Diet
To determine a possible connection, Canadian researchers observed 204 cohabiting couples over a period of three months. Both partners had to fill out questionnaires about their sleep and diet at the start of the study and again after one and three months. During the first 14 days, participants also kept a daily journal to record how much they focused on healthy eating.
The average age of participants was 42 years. In each couple, at least one person was overweight or obese, with a body mass index of 25 or higher, and was trying to improve their diet or physical activity.
These Are the Most Interesting Findings
Overall, 96 percent of study participants reported trying to change their diet. While participants’ eating habits slightly improved during the study, their sleep quality did not fundamentally change. Additionally, women more frequently reported healthier eating and greater efforts in this regard than men. However, there was no evidence that gender influenced how one partner’s sleep affected the other’s diet.
Researchers found another important connection. Data analysis showed that participants who slept poorly were less able to achieve their healthy eating goals. Those with poor sleep reported making less effort to eat healthily and had less confidence in reaching their dietary goals. Interestingly, even those who slept well reported similar negative impacts on their diet if their partner slept poorly. This indicates that a partner’s sleep quality significantly influences one’s own diet.
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Why Does a Partner’s Poor Sleep Affect Your Diet?
But why does a partner’s sleep also influence your eating habits? The researchers don’t have a definitive explanation but have a hypothesis: “This is likely because the sleep-deprived partner is more likely to confront you with very tasty and high-calorie foods: things like crackers, chips, chocolate, or sweets,” the researchers noted in their study analysis. This means that those who sleep poorly tend to eat unhealthier during the day, which in turn leads their partner to eat less healthily.
According to the researchers, the social contexts in which unhealthy eating habits develop must be considered. One partner can influence the other’s eating behavior—consciously or unconsciously. Therefore, it’s important for both partners to focus on healthy eating together, even if only one of them wants to lose weight.
However, the researchers point out that their study does not prove that poor sleep leads to an unhealthy diet. This is an observational study based on participants’ self-reports. The Canadian scientists suggest that further studies should use more objective methods to measure sleep and diet to verify their results. This includes examining factors such as food selection in the household, meal planning, partner support, and conflicts.
Generally, Sleep Quality Improves With a Partner
On the other hand, previous studies have shown that having a partner in bed can contribute to better sleep quality. This, in turn, has positive effects on our health (as reported by FITBOOK). Participants who shared a bed with their partner reported less fatigue, easier falling asleep, and overall longer sleep. This ultimately also affected mental health, as this group of study participants showed better scores on depression, anxiety, and stress compared to those who slept alone.