Sleep varies from person to person, and what may be enough sleep for you may be too little or too much for the next person. A recent study by card payment provider Dojo found that 26 influential entrepreneurs, including Anna Wintour, Michelle Obama, Kylie Jenner, and Beyoncé, do.

The team analyzed interviews, social media, biographies, and other articles to draw out each person's 24-hour routine and sleep patterns.

According to the study, Rihanna sleeps on average from 1:00 a.m. to 6:00 a.m. and compensates for her day's fatigue with a nap. Makeup entrepreneur Kylie Jenner sleeps from 11 pm to 5 am, and Arianna Huffington goes to bed around 10:30 pm and wakes up at 7 am. When writing about her morning routine, Huffington revealed that she gets eight hours of sleep a night 95 percent of the time, and as a result, she is able to wake up 95 percent of the time without an alarm.

Oprah also wakes up naturally, usually going to bed at 10 p.m. to write in her gratitude journal and waking up around 6 a.m. Facebook COO Sheryl Sandberg and home organization guru Marie Kondo spend the most time in bed, going to sleep around 9:00-9:30 PM and waking up around 6:00 AM. [Sleep and health go hand in hand, and good sleep enhances concentration and productivity. What is surprising is that some of them seem to sleep less, but for them this may be enough.

The CDC recommends that most adults get seven to nine hours of sleep per night, but you may find that six hours is fine. When we spoke with sleep expert and neuroscientist Dr. Lindsey Browning about how to modify your sleep schedule, she said you shouldn't stress about trying to achieve any given number of hours. Instead, she said, it's about how you feel when you wake up - if you feel tired and unable to function well throughout the day, you need more sleep than you are getting now.

Speaking to Dojo about the new study's findings, Kate Mikhail, author of Teach Yourself to Sleep: A Former Insomniac's Guide to Sleep, and who spoke in a feature about how to sleep better, corroborated the findings: "During the day feel tired, overly emotional, more stressed than usual, frequently sick, falling asleep as soon as you put your head on the pillow - these are all signs that your mind and body may not be getting the sleep they need."

Sleep comfort also affects sleep. If you think your bed is causing you sleepless nights, check out our guide to the best mattresses. We also have a guide to the best pillows for every sleep style.

While some of the habits highlighted in the study are not recommended (working in bed is a major contraindication to good sleep), there are some great techniques to help you sleep better at night.

Award-winning artist and CEO of Fenty Beauty, Rihanna, seems to love power naps, but the key is when and how long you nap. The general rule is to nap by 3 p.m., but if your bedtime is very early, you may need to take your midday nap earlier than 3 p.m. If the desire for sleep (the need to sleep) is not increased before going to bed, it will take longer to fall asleep.

Michael, author of Insomnia, says, "Naps are an effective way to boost your energy and productivity during the day if you are not getting enough sleep at night. You can take a short power nap, a 26-minute NASA nap, or a full 90-minute sleep cycle if you are extremely sleep deprived."

I also like Vogue editor-in-chief Anna Wintour's approach of preparing for the next day before going to bed at night. Having an outfit, lunch, and to-do list ready to go helps me relax and sleep better because I have less to think about (and worry about) when I go to bed. Kayla Itsines, who recently sold her workout platform Sweat to iFit for $400 million, is also a fan of setting up a to-do list at night, which helps her fall asleep.

Mikael explains his rationale: "As with anything that shapes sleep, it's really helpful to know the basic science and biology. In this instance, the problem or concern is moving from the emotional amygdala to the rational and cognitive HQ, the prefrontal cortex." [Spanx founder Sarah Blakely and famous designer Vera Wong have been found to make taking a relaxing bath part of their evening routine. Journaling and meditation were also popular, allowing some entrepreneurs to switch from their hectic schedules. Whitney Wolf Heard, Marie Kondo, Oprah Winfrey, and Beyonce are reportedly fans of using these powerful relaxation and reflection methods before bed.

"One way to improve sleep and be more productive when you wake up is to actively unwind during the night. Cortisol is one of the biggest sleep disruptors."

"Taking a relaxing bath, changing into loungewear (if you don't already live in loungewear), and filling your evening with sleep habit cues that let you know your work is done can really help with this."