You check your Apple Watch in the morning. Sleep score: 62. You decide it's going to be a foggy day. And then it is. A 2014 Colorado College study suggests the score itself causes the fog. 164 people walked into a lab. Researchers hooked them up to fake EEG equipment and told them the readout would show their REM percentage from the night before. Then they fabricated a number. Half the room was told 28.7%. Half was told 16.2%. The machine wasn't measuring anything. Participants took four cognitive tests. The Paced Auditory Serial Addition Test, where you add numbers spoken at increasing speed and hold your last sum in working memory while computing the next. And the Controlled Oral Word Association Task, where you generate as many words as you can starting with a single letter under time pressure. Both are gold-standard measures of attention and executive function used in clinical neurology. The 28.7% group outperformed the 16.2% group on both. Significantly. How rested participants actually felt that morning predicted nothing. The mechanism is mindset priming an executive resource. When you believe you slept well, you allocate cognitive effort more aggressively. You don't conserve. You don't pre-disengage. Belief about the resource changes how you spend it. Two control conditions ruled out demand characteristics. Participants weren't trying harder because they thought they should. Real measurable cognitive performance shifted with the number on the readout. The Apple Watch sleep score. The Oura ring readiness number. The morning ritual of checking either one is taxing the resource you're about to need. The performance gap from a fabricated REM percentage was larger than the gap from how rested participants actually felt. The number was louder than the night.

The lines at Atlanta airport are not to be believed. Imagine showing up 3-4 hours early, and still missing your flight.

The lines at Atlanta airport are not to be believed. Imagine showing up 3-4 hours early, and still missing your flight.

WHAT THE ACTUAL FUCK

Claude Code wiped our production database with a Terraform command. It took down the DataTalksClub course platform and 2.5 years of submissions: homework, projects, and leaderboards. Automated snapshots were gone too. In the newsletter, I wrote the full timeline what I changed so this doesn't happen again. If you use Terraform (or let agents touch infra), this is a good story for you to read. alexeyondata.substack.com/p/…

Adulthood is just getting letters from a company that you've never heard of, telling you they leaked your data that you didn't know they had, and including a multi-step to-do list for you to protect the data that they did not.

I hate when there’s a layoff news on the TL and people start giving advice on working harder or being indispensable. What makes you think the people affected were not hardworkers? It’s too annoying

a whole new generation of developers is about to discover the difference between creating software and maintaining software

I work at Slack. We tell employees their DMs are private. And they are. Mostly. Look, when we say "private" we mean private between you and the person you're messaging. And your admin. And HR. And legal. And whatever compliance tool your company bought. And the export logs. And the backup systems. And anyone with a court order. But other than that, totally private. We're very clear about this in our documentation. Page 47. Section 12. Subsection C. Paragraph 8. The part nobody reads before they trash-talk their manager at 11pm. Here's what employees don't understand. When you delete a message, you're just deleting it from your view. The message still exists. In exports. In backups. In the retention policy. It's like closing your eyes and thinking you're invisible. The data belongs to the company, not you. We say this right in our terms. Workspace owners control everything. They decide how long messages are stored. Sometimes it's 30 days. Sometimes it's forever. Hope you didn't say anything spicy in 2019. Enterprise customers get extra features. Full message exports. Metadata tracking. Who messaged whom. When. How often. Communication patterns. It's for "compliance." It's for "legal needs." It's for "regulatory requirements." It's definitely not for micromanagement. We're very careful to explain that admins can't see messages in real-time. They have to formally request an export. Fill out some forms. Click some buttons. Maybe wait an hour. Very high barrier. Almost impossible to abuse. The key takeaway is simple. Treat Slack like work email. Not like WhatsApp. Not like Signal. Just because it looks like a chat app doesn't mean it works like one. If a message could cause trouble when HR reads it, don't send it. This is empowering employees with knowledge. If you wouldn't say it in the break room with your manager behind you, don't type it in Slack. That's privacy. Informed privacy. Enterprise-grade informed privacy.