Sleep Is the First Domino

I tracked my mood and sleep for over six months. The pattern that emerged was brutal, obvious, and something no doctor had ever explained this clearly.

I want to tell you something that took me embarrassingly long to figure out.

When I don’t sleep well, I don’t just get tired. I become a different person. More irritable, less patient, quicker to snap at people I care about. And for the longest time I thought that was just… me having a bad day. Like everyone else.

It’s not.

The pattern I didn’t want to see

I’ve been tracking my mood, energy, and sleep daily for a while now. Not perfectly — there are gaps, weeks where I forgot or just didn’t feel like it. But enough data accumulated that patterns started showing up whether I wanted them to or not.

Here’s what I found: out of roughly 14 nights where I slept less than 6 hours, about a third of them were followed by a noticeable mood drop the next day. Another third showed no change at all. And the rest actually preceded a mood increase — which sounds like good news until you realize that in bipolar, a mood spike after no sleep isn’t a good thing. It’s a warning sign.

But the real insight wasn’t in the averages. It was in the sequences.

Sleep deprivation didn’t directly tank my mood every time. What it did was strip away my ability to handle things. On a full night’s sleep, I could deal with a stressful commute, a difficult conversation, an unexpected problem at work. On 5 hours? That same commute made me furious. That same conversation turned into a fight. The problem at work felt like a personal attack.

Sleep wasn’t predicting my mood. It was predicting my capacity to regulate.

And that distinction matters, because it means the damage doesn’t show up right away. You don’t wake up after a bad night and think “I’m in danger.” You wake up and think “I’m fine, just a little tired.” Then something normal happens and you blow up, and you can’t understand why.

Two bad nights is all it takes

There’s a specific pattern I’ve noticed in myself, and I’ve talked to enough people with mood disorders to suspect it’s not just me.

One bad night — you’re okay. You compensate. You push through. You might even feel kind of wired and productive, which is its own trap.

Two bad nights in a row — that’s when things start breaking. Your emotional responses stop matching the situation. Small irritations become big ones. You say things you normally wouldn’t. And the worst part is you know you’re being unreasonable, but you can’t stop it. The insight is there, but the control isn’t.

I remember one stretch where I’d slept about 5 hours for two nights running. Nothing dramatic had happened. Work was busy, travel was hectic, normal stuff. But I got into an argument with someone close to me and completely lost it. Just fury, for about an hour, over something that on any other day I would’ve handled calmly.

Afterwards I logged it. And looking back at the data, it was obvious. Two nights of 5 hours. Stressful day. Emotional blowup. The domino chain was right there in the numbers.

Why this matters more if you have a mood disorder

If you’re neurotypical and you don’t sleep well, you have a bad day. You’re grumpy, you drink more coffee, you go to bed earlier. It corrects itself.

If you have bipolar — or depression, or anxiety, or PTSD — sleep disruption doesn’t just make you tired. It can destabilize the entire system. For people with bipolar specifically, sleep loss is one of the most reliable early warning signs of a manic or hypomanic episode. It’s in the clinical literature, it’s in the DSM criteria, and yet somehow nobody hands you a simple tool to actually track it against your mood over time.

I’ve seen it in my own data. Periods where my sleep started fragmenting — 3 hours here, 4 hours there — lined up almost perfectly with my worst stretches emotionally. Not because the insomnia caused the episode necessarily, but because they’re part of the same cascade. Sleep goes first. Then energy gets weird. Then mood follows. Then behavior.

The dominos fall in order. Every time.

What actually helped

I’m not going to pretend I’ve solved this. I still have bad nights. But tracking it changed something fundamental about how I relate to my own mental state.

Before tracking, a bad day was just a bad day. I’d blame the situation, the person, the circumstance. After months of data, I started checking the sleep column first. And more often than not, that’s where the answer was.

Some things that have made a real difference for me:

The “no hard conversations after bad sleep” rule. This sounds simple but it’s genuinely hard to follow. When you’re running on 5 hours and something upsets you, every instinct says to address it now. The rule is: don’t. Wait until you’ve slept. The thing that feels urgent at 11 PM after two bad nights will feel manageable at 10 AM after a full rest. I don’t always follow this rule. But when I do, it works.

Treating two consecutive bad nights as a clinical signal, not a lifestyle inconvenience. If I have two nights under 6 hours, I now treat that the way you’d treat a fever. Not panic, but active response. Adjust the schedule, take the sleep aid if prescribed, cancel non-essential plans. The cost of overreacting to a sleep dip is a boring evening. The cost of underreacting can be a week-long mood episode.

Actually looking at the data. Not just logging it and forgetting. Sitting down once a week and looking at the sleep-mood relationship for the past 7 days. It takes 2 minutes. And it builds a kind of self-knowledge that no amount of introspection alone can match, because memory lies. Data doesn’t.

The thing nobody tells you

Here’s what I wish someone had told me years ago: sleep isn’t one factor among many. It’s the foundation that everything else is built on. Your medication works better when you sleep. Your therapy insights land better when you sleep. Your relationships are easier when you sleep. Your self-awareness is sharper when you sleep.

Every mental health professional I’ve ever seen has asked me “how’s your sleep?” at the start of every appointment. It took me years to understand that wasn’t small talk. That was them checking the foundation before looking at anything else.

If you take nothing else from this — start tracking your sleep alongside your mood. You don’t need an app for it. A notebook works. But do it consistently for a month and then look at the two lines together. I promise you’ll see something you didn’t know about yourself.

And if you do want an app that makes this easy and actually shows you the relationship between the two — well, that’s literally why I built Steadyline.

This is part of a series about what I’ve learned from tracking my mental health daily. I’m a software engineer who lives with bipolar disorder, and I’m building the tool I needed but couldn’t find. More at steadyline.app.