$user= User::find($user_id);

Log::info(print_r($user, true));

<?php

$user = User::find($user_id);

Log::error("Something happened to User {$user_id}.", ['object' => $user->toJson()]);

<?php

// User.php
[...]

class User
{
    [...]

    public function __toString()
    {
        return "{$this->id}";
    }
}

// [...]
$user = User::find($user_id);

Log::error("Something happened to User {$user}.", ['object' => $user->toJson()]);

Log::debug((array) $object);

/**
 * Format the parameters for the logger.
 *
 * @param  mixed  $message
 * @return mixed
 */
protected function formatMessage($message)
{
    if (is_array($message)) {
        return var_export($message, true);
    } elseif ($message instanceof Jsonable) {
        return $message->toJson();
    } elseif ($message instanceof Arrayable) {
        return var_export($message->toArray(), true);
    }

    return $message;
}

Log::emergency($message);
Log::alert($message);
Log::critical($message);
Log::error($message);
Log::warning($message);
Log::notice($message);
Log::info($message);
Log::debug($message);