There's More to Healthy Sleep than Getting 8 Hours: One Factor You May Be Overlooking

We've all heard about the importance of sleep duration, or the amount of sleep we're getting every night. However, studies show that sleep regularity is also of great importance when it comes to protecting your health. Sleep regularity refers to a pattern of consistent sleep and wake times (e.g. going to bed at 10pm and waking up at 7am every day with little variation). Turns out, having significant variation in the timing of sleep onset and offset from day-to-day is linked with poorer health and overall functioning.

Studies show that sleep regularity is also of great importance when it comes to protecting your health.

A 2023 review paper by the National Sleep Foundation consolidated evidence from 63 studies on sleep regularity. The authors found that inconsistent sleep and wake times were associated with a wide variety of negative behavioral changes and health conditions (here is a list of them, just to name a few):

Behavioral Changes Linked with Sleep Irregularity

• Sleepiness

• Alcohol Consumption

• Poorer Dietary Choices

• Sedentary Behaviors

• Drowsy Driving

• Risk Taking

• Poorer Academic Performance

• Decreased Reaction Time

Health Conditions Linked with Sleep Irregularity

• Poorer Sleep Quality

• High Blood Pressure and Cardiovascular Disease

• Depression

• Negative Mood

• Suicidal Ideation

• Obesity, Diabetes, and Other Metabolic Problems

• Neurologic Problems

• Gastrointestinal Problems

• Pain

It is common for adults to take advantage of "catch-up" sleep on the weekends/days off to compensate for shorter sleep durations the rest of the week. For this reason, the study also explored whether catch-up sleep may be beneficial. They found that catch-up sleep was associated with positive health outcomes such as better cardiovascular health and blood pressure, as well as decreased mortality. See the table below for the complete list of the health factors they analyzed in connection to catch-up sleep.

Fig. 4 Summary of associations between catch-up sleep and health outcomes measured. Numbers indicate the total number of publications in each category.

So, what explains the link between sleep regularity and better health? Inconsistent sleep and wake times create circadian misalignment, a state in which we are awake/consuming food at times when the body's internal clock is set to sleep mode.

Significant evidence shows that long-term circadian misalignment is detrimental to health. Our bodies have been designed to be asleep when it is dark and awake when it is light. However, modern-day society is loaded with stimuli that disrupt this natural pattern (think city lights, screeching cars by your window at night, LED lightbulbs, the TV blaring after dinner, easy access to food at all times for many Americans, and phones emitting artificial blue light). We've disobeyed our natural clocks by eating, sleeping, and exercising at odd and inconsistent times. These habits have major implications for metabolic and hormone health over time.

Inconsistent sleep and wake times create circadian misalignment, a state where we are awake/consuming food at times when the body's internal clock is set to sleep mode.

Here are the takeaways from the study: get into circadian alignment by maintaining consistent sleep and wake times (if possible, less than 30 minutes variation in sleep onset from day to day and sleep offset from day to day). Create a habit of consistent meal times, as well (e.g. breakfast at 7, lunch at noon, dinner at 6). If the demands of your job or other responsibilities make it impossible to get sufficient sleep during the week, it may be beneficial to sleep in for 1-2 hours per day on the weekends.

References:

DOI: 10.1016/j.sleh.2023.07.016