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In the news: Diet and Nighttime Lights Can Impact Sleep & Health

There are plenty of good reasons to strive for a better night’s sleep. For one thing, lack of sufficient sleep can affect concentration, mood, motivation, and judgment. Research also suggests that sleep plays a role in forming and storing memories. And ongoing lack of sleep has been linked to many chronic diseases.

It’s no wonder that research is actively trying to identify factors that could affect sleep quality. In fact, several recent studies suggest what we eat, and night-time lighting can impact sleep and, importantly, our health.

Med Diet Linked to Better Sleep Quality

In a newly published study(1), researchers assessed how closely 500 college students adhered to the Med diet pattern of eating and used a validated questionnaire to score the students’ quality of sleep.

About half of the students had medium or high adherence to the Med diet. Analysis revealed that students with good adherence were more likely to have good sleep quality. Those whose diets more closely matched the Med diet had significantly better subjective sleep quality, with less sleep latency (time to get to sleep), sleep disturbance, and daytime dysfunction.

They also categorized students by chronotype – the internal circadian rhythm that helps determine whether they are a ‘morning person’ (goes to sleep and awakes early), a ‘night person’ (goes to sleep and wakes up later), or intermediate (can be either morning or night type). Students with a morning chronotype were about 6 times more likely to have good adherence to the Med diet vs. the other two types.

A recent review of 20 previous studies on diet and sleep(2) generally agrees with the Med diet findings for students. The reviewers found that diets rich in fiber, fruits, vegetables, and anti-inflammatory nutrients and lower in saturated fat were associated with better sleep quality. They highlighted the Med diet as one that contained the main qualities tied to better sleep.

What attributes of a Med-like diet might contribute to a healthful sleep? One possibility is its anti-inflammatory nature, as increased levels of inflammation have been linked with poor sleep quality in previous studies. The Med diet provides anti-inflammatory nutrients such as antioxidants and omega-3 fatty acids. The diet is also rich in fruits and vegetables which are a source of sleep related melatonin and its precursor serotonin.

Light Exposure During Sleep Can Harm Health

Sleep experts have many suggestions for getting a better night’s sleep: be physically active to reduce stress, stick to a regular sleep schedule, and put away electronic devices before bed since they can interfere with sleep by suppressing melatonin production.

The results of another new study(3)suggest we should also shut the blinds, turn off lights – and keep them off – during sleep for better heart and metabolic health.

A total of 20 young adults participated in this study, which included two nights of sleep in dim light followed by a night of sleep with overhead room lighting.

Even one night’s sleep in a moderately lit room increased insulin resistance the following morning, Heart rate was higher and heart rate variability lower during sleep in the moderately lit room vs. dim light conditions.

Previous evidence has shown that nighttime light, either from outdoor or indoor sources, negatively impacts sleep quality. The results of the current study show that light at night can impair blood sugar and cardiovascular function – both of which raise the risk for heart disease and diabetes.

If you need a night-light for safety, the author suggests using a dim light (red or amber for less stimulation) that’s close to the floor. And if you can’t control outdoor light, try blackout shades or an eye mask.

References

1. Naja F, et al. Adherence to the Mediterranean Diet and its association with sleep quality and chronotype among youth: A Cross-Sectional Study. Front Nutr. Online, Jan 19, 2022.
2. Wilson K, et al. Diet composition and objectively assessed sleep quality: A narrative review. J Acad Nutr Diet. Online, Jan 19, 2022.
3. Light exposure during sleep impairs cardiometabolic function. PNAS. Online March 14, 2022.