If you think each of the seven days of the week is equal, think again.

Yes, each day is equally divided into 24 equal hours and each hour has 60 equal minutes. When it comes to the social-media behaviors of musicians and their fans, however, the days of the week are far from routine.

Data provided by Next Big Sound shows there are rhythms to the ways artists and people act online. The metric, loosely termed "periodicity," represents the day's share of the week's activity. (So, 14.8 means 14.8% of that week's activity on a particular service took place on that day.) Understanding the peaks and valleys in these behaviors can be advantageous in using online marketing tools.

Take Facebook, for example. An artist will post on Facebook hoping to get a maximum number of likes from followers and readers. According to Next Big Sound's data, Monday is the best day of the week in terms of average likes per Facebook post with 14.8. The average drops steadily to a low of 13.9 on Friday before increasing to 14.5 on Sunday, the week's second-highest average. So artists can expect to get the most likes on their Facebook posts on Mondays and Sundays.

The data is also mirrored for artists. The numbers show artists are almost uniformly active on Twitter during the week. They hit a weekday low of 14.6 on Monday and weekday highs of 15.1 on Wednesday and Friday. But on the weekend, artists' Twitter activity drops to 12.8 on Saturday and 12.5 on Sunday--that's more than a 15% drop from the midweek average. Fans' Twitter usage doesn't fall off nearly as much on weekends. Average daily Twitter followers, not shown on the graph here, drops only 5% on the weekend.

There's a lesson here for Twitter users: The weekend holds untapped opportunity. Artists may be busy with band practice or traveling to gigs. Label or management company staffers may not like to tweet as often on weekends. But the goal should be to tweet when your fans are likely to see it.

Other data confirms that weekends are busy. Artists get their highest share of new Instagram followers on Sundays and their least on Thursdays and Fridays. Fans also stream a lot of audio and video on the weekends. Artists' share of Vevo views peaks on Saturday, and their share of Internet radio impressions is highest on Saturdays and Sundays.