Here's why Tim Cook, Sallie Krawcheck and other successful people wake up at 4 a.m.

Successful people tend to wake up early.

Take Apple CEO Tim Cook, who starts his morning routine at 3:45 a.m.Or Sallie Krawcheck, Ellevest CEO and co-founder, who wakes up at 4 a.m. for creative thinking time.

Some other successful people also get a 4 a.m. start, including Pepsi CEO Indra Nooyi, Chrysler CEO Sergio Marchionne and first lady Michelle Obama.

It's arguably the most productive time of the day, according to The Wall Street Journal, because it allows you to tackle tasks before distractions arise.

"When you have peace and quiet and you're not concerned with people trying to get your attention, you're dramatically more effective and can get important work done," psychologist Josh Davis and author of "Two Awesome Hours" told the Journal.

By waking up well before the sun rises, you're essentially eliminating common distractions, such as text messages, emails and social media notifications. "No one is expecting you to email or answer the phone at 4 a.m.," Davis said. "No one will be posting on Facebook. You've removed the internal temptation and the external temptation."

Getting things done early will also give you more control over your life. "It gives you a sense of confidence that you, indeed, direct your life," said author Thomas C. Corley, who studied wealthy people for five years and found that many of them wake up at least three hours before their workday begins. "It gives you a feeling of power over your life. It puts the reins of 'your' life back into 'your' hands."

If you're ready to join the 4 a.m. club, start with pro tips from those who are already doing it.

"I sleep in gym clothes and put sneakers on within 10 seconds of waking up," entrepreneur Peter Shankman, who gets up at 4 a.m. to run, told the Journal. "It's very hard to go back to sleep once your shoes are on."

Another early bird has a programmable coffeemaker that starts percolating at 3:45 a.m.

If you're really not a morning person, Corley recommends finding someone else who will join you — an accountability partner.

Most importantly, don't wait. "Start tomorrow," he writes.