# Simulate different patterns
One way to understand your sleeping pattern is to compare it to a mathematical model. This page presents a series of simple models to help you think about how you might model your own sleeping pattern.
## An unrealistically simple model
We can model a year-long sleep diary by using a language called [JavaScript](https://developer.mozilla.org/en-US/docs/Web/JavaScript) to create 365 sleep events:
```javascript
for ( n = 0; n < 365; n = n+1 ) {
add_diary_entry({
asleep_at: n*days,
awake_at: n*days + 8*hours,
});
}
```
Click “run this simulation” to create a diary and view it in the dashboard. In this case, it will look like you slept between exactly midnight and 8am GMT every day. Notice that the graphs still show your local time, including your daylight savings time - you might like to change the timezone to _Etc/GMT_ instead.
## A more realistic model
People don't sleep at precisely the same times every day, which we can simulate by adding a bit of randomness to the start and end of sleep. Specifically, we use a [normal distribution](https://en.wikipedia.org/wiki/Normal_distribution) (bell curve) to produce something that looks more human:
```javascript
for ( n = 0; n < 365; n = n+1 ) {
add_diary_entry({
asleep_at: n*days + normal_distribution()*hours,
awake_at: n*days + normal_distribution()*hours + 8*hours,
});
}
```
## Trouble getting to sleep on time
Now we can simulate something that looks like a human sleeping pattern, we can see what sort of graph you would have if you went to sleep about 4am every day:
```javascript
for ( n = 0; n < 365; n = n+1 ) {
add_diary_entry({
asleep_at: n*days + normal_distribution()*hours + 4*hours,
awake_at: n*days + normal_distribution()*hours + 12*hours,
});
}
```
A new simulation runs every time you click the button - click it a few times and compare the results.
## Trouble sticking to a bedtime
Simulations can also show what it would be like if your bedtime advanced by a constant amount every day. Here's an example of what it would look like if your bedtime advanced by one hour per day:
```javascript
for ( n = 0; n < 365; n = n+1 ) {
add_diary_entry({
asleep_at: n*days + normal_distribution()*hours + n*hours,
awake_at: n*days + normal_distribution()*hours + n*hours + 8*hours,
});
}
```
## A complex model
We can even simulate more complex sleeping patterns. Here's a model that describes going to bed about 10pm on week days and midnight on weekends, and being woken up by an alarm clock at 6am during the week:
```javascript
for ( n = 0; n < 365; n = n+1 ) {
if ( day_of_week(n) == "Saturday" || day_of_week(n) == "Sunday" ) {
add_diary_entry({
asleep_at: n*days + normal_distribution()*hours,
awake_at: n*days + normal_distribution()*hours + 8*hours,
});
} else { // Monday to Friday
add_diary_entry({
asleep_at: n*days + normal_distribution()*hours - 2*hours,
awake_at: n*days + normal_distribution()*minutes + 6*hours,
});
}
}
```
## Create your own
Now you've seen some simulations, edit the block below to create your own:
For a complete list of available features, see [the simulation reference page](simulation-reference.md).