Increase energy, improve performance, and enhance interactions with colleagues with these simple adjustments to your daily schedule

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Whether it's flying or standing still, there's no question that time plays a vital role your daily life. Science-and the world around us-shows it: Medicine can be four to five times more effective in the early morning, alcohol has a greater effect on your ability to drive at 12 a.m. than 6 p.m., and more Olympic records are set in the evening hours than in the morning when body temperatures are higher and muscles are more limber.

Virtually anything you do has a different bodily effect depending on when you do it, says Matthew Edlund, M.D., and director of the Center for Circadian Medicine. That's because playing to the strengths of your circadian rhythm-or your body's natural clock-can boost your performance.

The problem: "Modern life makes it harder for us to stay on the rhythmic schedule our bodies are naturally meant to follow," says Steve Kay, Ph.D., a geneticist and professor of biological sciences at the University of Southern California. One way today's tech disrupts sleep: Using your smartphone before bed. A recent study at Michigan State University showed that using a smartphone after 9 p.m. cut into sleep time and participants were more tired at work the next day.

The good news? You can harness the power of time by tuning in to your natural biological clocks, Kay says. Follow this schedule to ensure your most productive workday yet.

6 a.m.: Wake Up



Surveys show that most highly successful CEOs, politicians, and business people wake up in the pre-dawn hours. These early birds, including President Obama, Margaret Thatcher, AOL CEO Tim Armstrong, and Gwyneth Paltrow, report rising at 6 a.m. or even as early as 4:30 a.m.

Kay explains that these high achievers' early wakeup times may be driven by social pressure to get things done, but it turns out there are also biological benefits to getting up early. According to Edlund, exposure to dawn light can have a positive impact on mood, and may even make it easier to get up since our internal body clocks can be nudged earlier by an increase of morning light.

7 a.m.: Get Your Java Jolt



There's a reason we drink coffee in the morning: It really does help us wake up, says Kay. Caffeine will coincide with your body's natural waking process, since it activates your sympathetic nervous system and stimulates the release of norepinephrine, a neurotransmitter responsible for concentration and cognitive alertness.

7:30 a.m.: Hit Send



Mark Di Vincenzo, timing expert and author of Buy Ketchup in May and Fly at Noon, advises sending important emails on Tuesdays, Wednesdays, or Thursdays. The reasoning? Mondays tend to be taken up by meetings, and people may be mentally checked out or on vacation on Fridays. Plus, emails sent later in the day tend not to get read until late in the afternoon or even the next day, so your best shot of someone opening your email is to send it in the first part of the day.

8:00 a.m.: Reach the Big Guy



You'll be more likely to reach a big shot at his desk if you call in the early morning, since secretaries probably aren't in yet at that hour, so higher-ups may answer their own phones at that time, explains Di Vincenzo. Furthermore, if you're calling a financial adviser, the best day to do so is Friday, as the weekdays are typically taken up with client meetings. Exception: Phone a lawyer in the afternoon, as they often put calls on hold in the morning hours, when they may be in court or in meetings, and are more likely to take and make calls in the late afternoon, Di Vincenzo adds.

9:30 a.m.: Hold a Team Meeting



Set up group get-togethers about 30 minutes after workers arrive, says Di Vincenzo. Bonus tip: Some research shows that picking an odd time-10:35 a.m. or 2:40 p.m.-can be more effective in ensuring employees' arrive on time since they'll be paying closer attention to the clock. If a meeting starts at 11 a.m., employees may reason it starts at "around 11" so it's alright to arrive at 11:05 a.m, Di Vincenzo explains.

10:30 to 11:30 a.m.: Tackle a Tough Assignment



Studies show that mental sharpness reaches its peak in the late morning, since your rising body core temperature causes alertness to go up, says Edlund. This makes this time ideal for starting any task that requires mental effort-whether it's negotiating a complex deal, preparing a presentation, or writing a complicated report.

2 p.m.: Go Ahead, Check Facebook



Don't blame your turkey sandwich for your post-lunch slump. "Our bodies' circadian rhythms cause energy levels to naturally take a dip after lunchtime, which makes the early afternoon a good time for less mentally taxing activities like checking social media," says Kay. Use this post-lunch period to take a (quick!) break to scroll through #TBT posts on Instagram or check our your friend's honeymoon photo album on Facebook. And there's no need to feel bad about it: Studies show that allowing employees who have access to social media sites during the day are 10 percent more efficient.

2:30 p.m.: Take a Quick Walk



That dragging feeling that crops up after lunch? Squash it in a snap simply by getting some fresh air. "Physical activity can overcome mental fatigue in as little as a 10 minute walk, leaving you more energized," says Edlund. If heading outdoors isn't an option, try pacing around your office as you talk on the phone or stopping by a coworker's desk to ask a question instead of emailing.

3 p.m.: Schedule a Job Interview



At this time, both you and the interviewer are more likely to be alert as mental acuity also peaks in the later afternoon, explains Di Vincenzo. (Scheduling a meeting for 11 a.m. can have a similar effect.) Just avoid going in right after lunch when people can be groggy.

4 p.m.: Tweet!



If going viral is your aim, hold that tweet until the 4 o'clock hour. Studies show this the best time to tweet if you're hoping for reads and retweets, Di Vincenzo says. As the day winds down, people start to mentally check out and drift onto social media feeds before they leave work.

4:30 p.m.: Voice a Complaint



Shoot for Thursday or Friday: "Behavioral science suggests your boss will be more likely to lend a sympathetic ear as the weekend approaches," says Di Vincenzo. Even more: "Temperaments tend to improve in the late afternoon," says Edlund. But keep in mind this varies depending on the type of day your boss had, so keep her personality-and schedule-in mind.

5 p.m.: Ask for a Raise



Studies suggest that times as specific 4:30 or 5 p.m. (again, late in the week) may be best. Not only will your supervisor likely be in a better mood, but he'll also have gone through the majority of his to-do list and will be better able to better focus on you, says Di Vincenzo.

6 p.m.: Have a Cold One



Turns out, there's a scientific reason why happy hour makes us feel so, well, happy. "Early evening is a good time to socialize according to our biological clocks," says Kay. Your body temperature is starting to come down from the day's exertions so you're more relaxed and less stressed, but the production of melatonin (a sleep-inducing chemical) hasn't kicked in so you're not yet feeling sleepy.

7 p.m.: Schedule a Business Dinner



Di Vincenzo suggests taking a client on Tuesday nights since restaurants are traditionally slower, and you'll be more likely to score a table and have attentive servers. Also, food deliveries usually arrive over the weekend or on Monday, so the meal is likely to be freshest that day as well.