After you’ve determined what to learn and how much to learn, you might wonder when you should do your study. In one sense, it doesn’t matter at all; in terms of study effectiveness, there seems to be little conclusive difference between study routines carried out at different times of day. But in another sense, it matters a great deal: using Anki at maximum effectiveness requires a strong study habit, and here, when you study makes a big difference. Let’s take a look at that.
As I’ve alluded to in previous posts, I believe the number-two rule of learning with Anki is review every day. (The number-one rule is to learn something meaningful and worth learning, because as management guru Peter Drucker famously said, there’s nothing so useless as doing efficiently what should not be done at all.) If you can get yourself to review every day, everything else will more or less follow. If you can’t get yourself to review every day, studying becomes more difficult and less effective and you likely will not be able to maintain the motivation to continue using an SRS in the long run. In comparison, little else matters.
Now, it’s not as if the whole system will crash and burn and you’ll have to start over from the beginning if you forget to review next Tuesday; in the grand scheme of things, everything will be fine. But you also really don’t want to skip days if you can help it, because any cards you don’t review on Tuesday will be due on Wednesday, in addition to all the cards that were due Wednesday anyway. That means you’ll have approximately double the number of cards to review, plus you’ll be more likely than normal to have forgotten all of Tuesday’s cards.
It would be easy to blame this pile-up on Anki – and new users who haven’t read a series of blog posts on spaced repetition often do – but it’s a design flaw of your memory, not Anki! Anki certainly could be designed to apparently magic away your missed day, but it turns out this is a terrible idea. I discuss the problems with various forms of rescheduling overdue cards in the post on catching up.
If you think you can’t study while you’re on vacation, mobile apps like AnkiMobile make it easy to squeeze in at least a few reviews. If anything, vacations often make for more dead time than daily life; I’ve caught up on overdue reviews on many trains and buses. Of course, if you don’t want to study while you’re on vacation, that’s another matter… but the little green number you see when you get back might make you want to next time!
If you know in advance that you’re going to miss some days of study, Anki will allow you to review ahead: open the deck you want to study early, click the Custom Study button at the bottom, and choose the Review ahead preset. Most other SRS’s have similar options. Reviewing ahead is less efficient than reviewing on time, just as reviewing late is less efficient than reviewing on time, but if you know you aren’t going to be able to review on time, it can help to make your backlog less painful when you get back. (Curiously, reviewing too often can make your memory weaker, not just cause reviews to take more time overall – perhaps because you don’t have to think as hard to remember something before you’re close to forgetting it. So don’t review early because you’re bored… but if you were thinking about doing that, you should find a new hobby.)
Choosing a time of day
Since we’ve established that in comparison to studying every day, nothing else matters, the main consideration should be when you can effectively fit your SRS into your daily routine. If you figure you’ll just kind of do it whenever, you’re probably going to outright forget on a regular basis, and it becomes much easier to brush off. Similarly, if you pick a time to review that makes you miserable, whether that’s right after you get up when you’re not a morning person or in the middle of a break where you want to be doing something else, Anki will start to feel like a chore instead of a fulfilling and useful tool. I typically do my reviews over a cup of tea in the morning, which usually takes me about 10 to 15 minutes and is a great way of waking up my brain before I go to work. (To make time without getting up incredibly early, I have a later breakfast during my morning break.) For many years, I studied right before bed and that worked well too; again, the important thing is consistency.
AnkiMobile, the official iPhone app for Anki (or the unofficial but well-supported AnkiDroid, if you have an Android phone), offers another option: you can fit most if not all of your reviews in during the day while you’re commuting by public transit, waiting in line, taking a break at work, etc. Anki and smartphones are pretty much made for each other; cards fit perfectly on the screen, you can effectively review for as little as a few seconds, and it’s much more comfortable to tap on a phone in your lap than keep your hand perched over the keyboard for 20 minutes. I do nearly all my reviews on my phone even when I’m sitting at home.
If you do most of your cards on mobile during the day, it’s probably a good time to also have some time set aside in the evening in case you have less idle time than usual or you spend the whole Saturday at home watching Netflix. AnkiMobile offers an option to send a notification at some time of day when you have due cards; I have this option set to go off at 8 PM to catch days when I inadvertently forgot to do my reviews in the morning or didn’t get around to finishing them during the day. You can find this option in Settings > Review > Notifications.
OK, but what’s really best?
Supposing you’re thoroughly committed to spaced repetition, and you’re sure you can make yourself review regularly at whatever time yields the best mental performance… does it matter? Well, most studies suggest it doesn’t matter much, and to make matters more confusing, people’s interpretations disagree. Many people, including me, find their retention rate winds up slightly higher when they study early in the morning – perhaps they’re fresher and more concentrated. However, research suggests that studying just before going to bed is best for memory consolidation. (But looking at a computer screen just before going to bed is definitely bad for your sleep quality, which won’t help your memory, or your health!)
In summary, my interpretation is that nobody has a clue, and you should do whatever is easiest for you or whatever you enjoy most. If there is an effect at all, it’s unlikely to be large enough to matter. Studying with Anki is already an order of magnitude more effective than conventional study. If you’re chasing small gains, writing better flashcards, chasing down bad flashcards and improving them early, using mnemonics, and doing controlled experiments on small tweaks to the scheduling parameters are all likely going to give you better results.
If you’re curious, after you’ve been studying for a while at different times of day, you can check the Hourly Retention graph in Anki’s statistics to see how retention by time plays out for you. Who knows, maybe you’ll see a massive difference you can’t explain any other way – although I’ll point out retention percentage at review time is not necessarily the same thing as most effective study; perhaps the results of a “good” or “bad” study time only show up at the next review, or weeks down the line, which this statistic wouldn’t capture.
Note: Gwern’s article on spaced repetition comes to a similar conclusion, and it also includes a variety of references on memory consolidation that might interest the optimizers at heart.